First of all thank you for all you replies.

With regard to you Demon:
*Yes, I use capital letters for the files.
*Yes, I have selected to use PBPL (get the message when it is compiled).
*Yes, I am using an PIC18 part (specific PIC18F26K80).
*And yes, I also found what the error codes represents and as you stated they aren't so much of a help.

With regards to mackrackit:
As you can see in the code below, i have specified your line directly after I include the SDFS file.
And i use a 2GB card and it is in FAT format (and that will be FAT16, according to Microsoft).

I have already established that all my IO works, but today I am gonna try to monitor the data that is send
to the SD card and what he will send back

Code:
'configuration bits   
#CONFIG
    CONFIG  RETEN = ON          ; Ultra low-power regulator is Enabled (Controlled by SRETEN bit)
    CONFIG  INTOSCSEL = HIGH    ; LF-INTOSC in High-power mode during Sleep
    CONFIG  SOSCSEL = HIGH      ; High Power SOSC circuit selected
    CONFIG  XINST = OFF         ; Disabled
    CONFIG  FOSC = INTIO2       ; Internal RC oscillator
    CONFIG  PLLCFG = ON         ; Enabled
    CONFIG  FCMEN = ON          ; Enabled
    CONFIG  IESO = OFF          ; Disabled
    CONFIG  PWRTEN = ON         ; Enabled
    CONFIG  BOREN = SBORDIS     ; Enabled in hardware, SBOREN disabled
    CONFIG  BORV = 3            ; 1.8V
    CONFIG  BORPWR = ZPBORMV    ; ZPBORMV instead of BORMV is selected
    CONFIG  WDTEN = ON          ; WDT controlled by SWDTEN bit setting
    CONFIG  WDTPS = 512         ; 1:512
    ;CONFIG  CANMX = PORTB      ; ECAN TX and RX pins are located on RB2 and RB3, respectively
    ;CONFIG  MSSPMSK = MSK7     ; 7 Bit address masking mode
    CONFIG  MCLRE = ON          ; MCLR Enabled, RE3 Disabled
    CONFIG  STVREN = ON         ; Enabled
    CONFIG  BBSIZ = BB2K        ; 2K word Boot Block size
    CONFIG  CP0 = OFF           ; Disabled
    CONFIG  CP1 = OFF           ; Disabled
    CONFIG  CP2 = OFF           ; Disabled
    CONFIG  CP3 = OFF           ; Disabled
    CONFIG  CPB = OFF           ; Disabled
    CONFIG  CPD = OFF           ; Disabled
    CONFIG  WRT0 = OFF          ; Disabled
    CONFIG  WRT1 = OFF          ; Disabled
    CONFIG  WRT2 = OFF          ; Disabled
    CONFIG  WRT3 = OFF          ; Disabled
    CONFIG  WRTC = OFF          ; Disabled
    CONFIG  WRTB = OFF          ; Disabled
    CONFIG  WRTD = OFF          ; Disabled
    CONFIG  EBTR0 = OFF         ; Disabled
    CONFIG  EBTR1 = OFF         ; Disabled
    CONFIG  EBTR2 = OFF         ; Disabled
    CONFIG  EBTR3 = OFF         ; Disabled
    CONFIG  EBTRB = OFF         ; Disabled
#ENDCONFIG

'alias PIC pins definition 
    OP1         var PORTC.1     'For JUMPER1
    OP1_TRIS    var TRISC.1
    TX1         var PORTC.0
    TX1_TRIS    var TRISC.2
    OP2         var PORTB.4
    OP2_TRIS    var TRISB.4
    RX1         var PORTC.2
    RX1_TRIS    var TRISC.2
    
    OP3         var PORTB.2     'For JUMPER2
    OP3_TRIS    var TRISB.2
    TX2         var PORTB.3
    TX2_TRIS    var TRISB.3
    OP4         var PORTB.0
    OP4_TRIS    var TRISB.0
    RX2         var PORTB.1
    RX2_TRIS    var TRISB.1
    
    OP5         var PORTA.3     'For JUMPER3
    OP5_TRIS    var TRISA.3
    TX3         var PORTA.2
    TX3_TRIS    var TRISA.2
    OP6         var PORTA.6
    OP6_TRIS    var TRISA.6
    RX3         var PORTA.7
    RX3_TRIS    var TRISA.7
    
    SHTDWN      var PORTA.1     'Shutdown 3.3V regulator
    SHTDWN_TRIS VAR TRISA.1 
    
    SD_WE       var PORTC.6     'SD card Write Protect 
    SD_WE_TRIS  var TRISC.6     'SD card Write Protect direction
    SDI         var PORTC.4     'SPI data in
    SDI_TRIS    var TRISC.4     'SPI data in direction
    SCL         var PORTC.3     'SPI clock
    SCL_TRIS    var TRISC.3     'SPI clock direction
    SD_CS       var PORTA.5     'SD card Chip Select
    SD_CS_TRIS  var TRISA.5     'SD card chip select direction
    SD_CD       var PORTC.7     'SD card Detect
    SD_CD_TRIS  var TRISC.7     'SD card detect direction
    SDO         var PORTC.5     'SPI data out
    SDO_TRIS    Var TRISC.5     'SPI data out direction
        
    Rail_v      var PORTA.0     'incomming 5V rail
    Rail_v_TRis var TRISA.0
    
    LED         var PORTB.5     'Status LED
    LED_TRIS    var TRISB.5    

    MCLR        var PORTE.3     'MCLR 
    
    PGD         var PORTB.7     'PGD programming data
    PGD_TRIS    var TRISB.7
    PGC         var PORTB.6     'PGC programming clock
    PGC_TRIS    var TRISB.6

'includes:
    include "SDFS.bas"          ' include for using FAT16-SD card
    'include "SDFShc32d.pbp."
    SDC_UseHardSPI = FALSE 
    INCLUDE "DT_INTS-14.bas"    ' Base Interrupt System
    INCLUDE "ReEnterPBP.bas"    ' Include if using PBP interrupts
    include "modedefs.bas"
    
'defines for compiler
    DEFINE  LOADER_USED 0       'Not using a bootloader 
    define  OSC 16              'Tell PBP to expect 64MHz clock    
        
'watchdog settings
    WDTCON = 22                 'Set WDT to 2 s (default = 2 s)
    WDTCON.0 = 1                'enable watchdog
    
'oscillator settings
    OSCCON = %01110000          'Set internal clock to 16 MHz  
    'OSCTUNE = %11000000         'enable PLL (clock = now 64 MHz)
    
'interrupt settings
    INTCON = %00000000          'disabled all interupts 
    
'option settings

'analog i/o port settings     
    ANCON0 = %00000001
    ANCON1 = %00000000 
    SLRCON = %00000000
        
'digital i/o port settings 
    PADCFG1 = %00000000         'disable pull-up  
    WPUB = %00000000            'disable pull-up  
    ODCON = %00000000           'disable open-drain  
    TRISA = %00010101           'Port A
    TRISB = %11001000           'Port B      
    TRISC = %11010001           'Port C
    
'adc settings
    ADCON0 = %00000001
    ADCON1 = %00110000          'Use internal 4.1 refference
    ADCON2 = %10000000          'Right justified
     
'uart settings

           
'spi settings
       
'timer2
    T2CON = %01111111           'postscaler=16,timer on, prescaler=16 (62500 Hz)     
    PR2 = 251                   'comperator value is set to divide by 251(250 Hz)
    PIR2.1 = 0                  'reset flag
         
'constant definition
    FIRMWARE_VERSION_M  con 00  ' M + . + S is the firmware version -> XX.XX
    FIRMWARE_VERSION_S  con 10
    
    log_control_max     con 53  'Maxmimum data to be received from control board
    log_pumpfix_max     con 11  'and pumpfix board after logging reqeust
    log_row_bytes       con 67  'Add log_control and log_pumpfix + carriage return and 2 tabs
    Startup_control_max con 1   'Maximu data to be received from control after start up request
    log_general_max     con 207 'Maximum of data that is contained in the general information block 
    log_info_banner     con 229 'maximum of data that is contained in the infromation banner for the logging
    log_ofset_bytes     con 436 'Ofset in bytes for log data to be stored : log_general_max + log_info_banner
    MAX_NOEN            con 8000'max of log entries, after that a new file has to be created (~500 MB)
    MAX_files           con 3

    File_PN_L           con 10  'Following numbers represents the maximum number 
    File_SN_L           con 9   'of bytes (LENGTH) that can be written to the 
    File_FV_L           con 5   'file for each point in the general information 
    File_TSO_L          con 6   'banner.
    File_TSON_L         con 6   'One byte represents one decimal value in a .txt
    File_TT_L           con 10  'file.
    File_NOER_L         con 9
    File_NOEN_L         con 4
    
    File_PN_S           con 15  'Following numbers represents the first (START)  
    File_SN_S           con 43  'possistion (byte) of the corresponding general  
    File_FV_S           con 72  'information. 
    File_TSO_S          con 98  'All the given numbers are measured from the 
    File_TSON_S         con 116 'starting point (0) in the file.
    File_TT_S           con 137
    File_NOER_S         con 167
    File_NOEN_S         con 197 
        
'variable definition
    TimerTick_max       var word'variable to contain needed interval
    TimerTick_counter   var word'variable that counts the interval
    LED_blink_counter   var byte'variable for pulses on the error LED
    i                   var byte
    
    log_control_data    var byte [log_control_max]      'array for received data
    log_pumpfix_data    var byte [log_pumpfix_max]      'array for received data
    strtup_control_data var byte [Startup_control_max]  'array for recived data 
    AN0_value           var word'variable to store ADC value of 5V rail     

    files_found         var word'For indexing the number of files
    
    File_PN             var byte[File_PN_L]     'Variables to write to the 
    File_SN             var byte[File_SN_L]     'SD card when there needs to
    File_FV             var byte[File_FV_L]     'be a new file to be 
    File_TSO            var byte[File_TSO_L]    'generated
    File_TSON           var byte[File_TSON_L]
    File_TT             var byte[File_TT_L]
    File_NOER           var byte[File_NOER_L]
    File_NOEN           var byte[File_NOEN_L]
    
    Current_TSO         var long'Current values that are read out from the file 
    Current_TSON        var long'on the SD card. These wil also be used for 
    Current_TT          var long'general values to be written to the file
    Current_NOER        var LOng 
    Current_NOEN        var word 
    Current_NOER_last   var byte

'hardware initialisation    
    SHTDWN = 0
    LED = 0
'software initialisation, setting variables at their initial value
    TimerTick_max = 15000       'is 60 seconds    
    TimerTick_counter = 0       'Set counter to 0
    LED_blink_counter = 0       'For indicating error
    files_found = 0
    Current_TSO = 0
    Current_TSON = 0
    Current_TT = 0
    Current_NOER = 0
    Current_NOEN = 0
    
    
    pause 10000 
'interrupt settings
ASM
INT_LIST  macro    ;    IntSource,  Label,                  Type,   ResetFlag?
         INT_Handler     TMR2_INT,   _TimerTick,             PBP,    yes           
    endm
    INT_CREATE                  ;Creates the interrupt processor
ENDASM
@ INT_ENABLE        TMR2_INT    ;enable Timer 2 interrupts

'---[Main]----------------------------------------------------------------------
Main:
    LED = 0                     'indicate start up procedure 
                                   
    gosub FSInit                'initialise the SD card
    Serout2 PORTB.1, 84, ["Init: ", FAT_error, " ", SDC_status, " ", SDC_response, $d, $a]
    gosub SD_error_check        'Check for errors on SD card
    gosub FINDfirst             'Look for files on SD card
    While(FAT_error = 0)        'Find next file on card
		files_found = files_found + 1
		Gosub FINDnext	       
	Wend