Latched buttons

[peu]

I just wrote this program to start learning on interrupt, as expected... it didn't work

@ device pic12F675, intrc_osc_noclkout, wdt_on, mclr_off, protect_off

DEFINE OSC 4

trisio  =%00110000
ansel   =%00000000  
cmcon  =%00000111  'Comparators Off
intcon  =%10001100  'interrupts enable / tmr0 overflow / gpio change interrupt enable
OPTION_REG = %11010101    ' Set TMR0 configuration

but1    var gpio.4
but2    var gpio.5
led1    var gpio.1
led2    var gpio.2
ledwork var gpio.0

but1st  var bit
but2st  var bit

conta   var byte


on interrupt goto interrupcion

loop:

for conta=0 to 255 step 16  'working led rise routine
    pwm ledwork, conta, 10
        disable
        if but1st=1 then
            but1st=0
            high led1
        endif
        if but2st=1 then
            but2st=0
            high led2
        endif
        enable
    
next conta
high ledwork

for conta =0 to 100
    pause 10
next conta

low led1    'set status buttons leds off
low led2

for conta=0 to 255 step 16  'Fall routine
    pwm ledwork, 255-conta, 10
        disable
        if but1st=1 then
            but1st=0
            high led1
        endif
        if but2st=1 then
            but2st=0
            high led2
        endif
        enable
   
next conta
low ledwork

low led1   'set button status leds off
low led2

goto loop


disable
interrupcion:
    but1st=but1
    but2st=but2
    intcon  =%10001101
    resume
enable

Any help appreciated


Pablo