Microcode studio - PIC16F877A Interrupts

Hello. I am trying to learn how to use the timer interrupts on the PIC16F877A. I have never used the timer registers before so I may be doing something wrong. I've searched the internet trying to find examples to go by and I've come up with a small program. It compiles in my software but when it is programmed to the PIC it won't display my variables on the LCD. Here is the code that I have so far:

DEFINE OSC 20 ' Define 20MHz Oscillator
DEFINE LCD_DREG PORTB ' Set LCD Data port
DEFINE LCD_DBIT 4 ' Set starting Data bit (0 or 4) if 4-bit bus
DEFINE LCD_RSREG PORTB ' Set LCD Register Select port
DEFINE LCD_RSBIT 3 ' Set LCD Register Select bit
DEFINE LCD_EREG PORTB ' Set LCD Enable port
DEFINE LCD_EBIT 2 ' Set LCD Enable bit
DEFINE LCD_BITS 4 ' Set LCD bus size (4 or 8 bits)
DEFINE LCD_LINES 4 ' Set number of lines on LCD
DEFINE LCD_COMMANDUS 2000 ' Set command delay time in us
DEFINE LCD_DATAUS 50 ' Set data delay time in us
PAUSE 1000 ' Pause for one second for power stabilization

mS VAR WORD
S VAR WORD
Timer1 VAR WORD

SYMBOL GIE = INTCON.7 'Global Interrupt Enable bit
SYMBOL TMR1_Val = 65535 'Set the initial value of TMR1
SYMBOL TMR1_mS = 1 'Time period of TMR1
SYMBOL TMR1_Enable = PIE1.0 'TMR1 interrup enable
SYMBOL TMR1_Overflow = PIR1.0 'TMR1 overflow flag

ON INTERRUPT GOTO INTERRUPT_HANDLER 'Goto handler on interrupt

DISABLE INTERRUPT
MAIN:
GOTO INITIALIZE
REPEAT
UNTIL S = 60
S = 0
INTCON = $80 'Permanently disables interrupts until called again
GOTO MAIN 'Loop forever
ENABLE INTERRUPT

INITIALIZE:
'TMR1 Interrupt Operation
GIE = 0
TMR1_Enable = 0 'Disables TMR1 Interrupt
INTCON.6 = 1 'Peripheral Interrupts
T1CON.1 = 0 '1 = External clock input from pin RC0
'0 = Internal clock (FOSC/4)
'TRISC.0 = 1 'If external clock, set clock as an input
'HPWM 1, 128, 32000 'Set TMR1's external source
T1CON.2 = 1 '1 = Do not synchronize external clock input
'0 = Synchronize external clock input
T1CON.4 = 0 '11 = 1:8 Prescale value
T1CON.5 = 0 '10 = 1:4 Prescale value
'01 = 1:2 Prescale value
'00 = 1:1 Prescale value
'When T1CON.1 = 0 this bit is ignored.
'TMR1 uses the internal clock when TMR1CS = 0.
Timer1 = TMR1_Val '
TMR1_Enable = 1 '
T1CON.0 = 1 '
RETURN

DISABLE INTERRUPT 'Disables interrupts in handler
INTERRUPT_HANDLER:
GIE = 0 'Disable Global interrupts
IF (TMR1_Overflow = 1 && TMR1_Enable = 1) THEN
TMR1_Enable = 0
Timer1 = Timer1 + TMR1_Val
Timer1.LowByte = TMR1L
Timer1.HighByte = TMR1H
TMR1_Enable = 1
TMR1_Overflow = 0
ms = ms + TMR1_mS
IF (mS >= 1000) THEN
mS = mS - 1000
S = S + 1
ENDIF
ENDIF
LCDOUT $FE, 1 ' Clear display
LCDOUT $FE, 2 ' Return home (beginning of first line)
LCDOUT $FE, $0C ' Cursor Off
LCDOUT " ", DEC S, " S ", DEC mS, " mS" ' display elapsed time
RESUME 'Return to main program
ENABLE INTERRUPT 'Enable interrupts after handler
END

Anyone that could help me out with this I would greatly appreciate it. Thank you all in advance.

Your timer interrupt won't work if you disable global interrupt. Try changing to the below code to see if something is displayed first:


DISABLE INTERRUPT
GOTO INITIALIZE
ENABLE INTERRUPT

MAIN:

GOTO MAIN 'Loop forever