Stack Under flow

[Wayne]

I seem to have a problem with the stack.
But a stack under flow ??
When my program get to a return I get this message
"Stack under flow error occurred from instruction at 0x000126"
the return instruction is at 0x000126.
The tools are PIC Pro 2.46 MPLAB 7.20 and the device is 16F913
Just don't know where to start with this problem.
I start the program, it will go through the getkey loop 2 times
and then give me the stack error. then it resets and starts over.

************************************************** ****

Define osc 8
OSCCON = %01110001 'SET FOR INTERNAL CLK @8 MHz
WDTCON = %00000000
LCDCON = %01000000
LCDSE0 = %00000000
LCDSE1 = %00000000
ANSEL = 0
CMCON0 = $07


TRISB=%00001111 'set PORTb, 1=input, 0=output
TRISC=%11110000 'set PORTc, 1=input, 0=output
TRISA=%11100100 'set PORTa, 1=input, 0=output


PORTB.4=0 ' set portb pin 4 low for LED sink
PORTA.0=0
INTCON = %00000000 'Turn interrups off

kp VAR BYTE 'Key press value
kp1 VAR BYTE 'Key press
LED1 VAR PORTA.0
LED2 VAR PORTA.1
LED3 VAR PORTA.3
LED4 VAR PORTA.4
LEDCOM VAR PORTB.4
TESTPIN VAR PORTC.5
COL1 VAR PORTC.0 'KeyPad col1
COL2 VAR PORTC.1 'KeyPad col2
COL3 VAR PORTC.2 'KeyPad col3
COL4 VAR PORTC.3 'KeyPad col4
ROW VAR BYTE
i VAR BYTE 'for next variable

'************************************************* **
start:

LED1=0 '
LED2=0 ' set all leds to Off
LED3=0 '
LED4=0 '
LEDCOM=0
kp=16
kp1=0


LED1 = 1
Pause 500
LED2 = 1
Pause 500
LED3 = 1
Pause 500
LED4 = 1
Pause 500
LED1 = 0
LED2 = 0
LED3 = 0
LED4 = 0

main:
GoSub getkey

getkey:
kp1=0 'Clear kp1


'col4

PORTC=%00000111 'Make PORTC.3 low PINs .0.1.2 High
kp1 = PORTB & $0f
IF kp1=14 Then kp=13
IF kp1=13 Then kp=14
IF kp1=11 Then kp=15
IF kp1=7 Then kp=15
IF kp1<>15 Then debounce

'col3

PORTC=%00001011 'Make PORTC.2 low PINs .3.1.0 High
kp1 = PORTB & $0f
IF kp1=14 Then kp=3
IF kp1=13 Then kp=6
IF kp1=11 Then kp=9
IF kp1=7 Then kp=12
IF kp1<>15 Then debounce

'col2

PORTC=%00001101 'Make PORTC.1 low PINs .3.2.0 High
kp1 = PORTB & $0f
IF kp1=14 Then kp=2
IF kp1=13 Then kp=5
IF kp1=11 Then kp=8
IF kp1=7 Then kp=10
IF kp1<>15 Then debounce

'col1

PORTC=%00001110 'Make PORTC.0 low PINS .3.2.1 High
kp1 = PORTB & $0f
IF kp1=14 Then kp=1
IF kp1=13 Then kp=4
IF kp1=11 Then kp=7
IF kp1=7 Then kp=11
IF kp1<>15 Then debounce

GoTo nokey
debounce:
pause 50
row = PORTB & $0f
if row = $f then showkp
goto debounce

showkp: For i = 1 to kp
High led1
Pause 500
Low led1
Pause 500
Next i
'DTMFout PORTC.5,[kp]
nokey:

Return
end
'*************************************