Why this is not working ?

Code C - [expand]
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unsigned char milliSec = 0, i = 0;
 
//Timer0
//Prescaler 1:4; TMR0 Preload = 6; Actual Interrupt Time : 1 ms
 
//Place/Copy this part in declaration section
void InitTimer0() {
    OPTION_REG = 0x81;
    TMR0 = 6;
    INTCON |= 0x20;
}
 
void interrupt() {
 
     if(INTF_bit) {          //ZC occurs once every 10 ms
        INTF_bit = 0;
        i = 0;
        if(milliSec == 0) {
             GP5_bit = 1;
             Delay_us(50);    //INTF occurs once every 10 ms. So, it is safe to use 50 us delay
             GP5_bit = 0;
        }
        else InitTimer0();
     }
     
     if(T0IF_bit) {        //Timer interrupt occurs every 1 ms
        T0IF_bit = 0;
        TMR0 = 6;
        //Enter your code here
        if(i++ == milliSec) {
              GP5_bit = 1;
              T0IE_bit = 0;
              Delay_us(80);  // 50 us delay in a 1 ms timer interrupt is not a problem
              GP5_bit = 0;
        }
    }
}
 
void initialize() {
     INTEDG_bit = 0;
     INTF_bit = 0;
     INTE_bit = 1;
     PEIE_bit = 1;
     GIE_bit = ~GIE_bit;
     //milliSec = EEPROM_Read(0);              //There is no option to load eeprom file in Proteus for 12F683, So, uncomment this code while testing in hardware
     //Delay_ms(20);
}
 
void main() {
 
     ANSEL = 0x00;
     CMCON0 = 0x07;
     TRISIO = 0x07;
     GPIO = 0x00;
     IOC = 0x00;
     
     while (1) {
 
            if(GP0_bit) {
                Delay_ms(50);
                while(GP0_bit);
                if(milliSec < 9)++milliSec;
                //EEPROM_Write(0, milliSec);     //There is no option to load eeprom file in Proteus for 12F683, So, uncomment this code while testing in hardware
                //Delay_ms(20);
            }
            else if(GP1_bit) {
                Delay_ms(50);
                while(GP1_bit);
                if(milliSec > 0)--milliSec;
                //EEPROM_Write(0, milliSec);     //There is no option to load eeprom file in Proteus for 12F683, So, uncomment this code while testing in hardware
                //Delay_ms(20);
            }
            
            else if(GP3_bit) {
                Delay_ms(50);
                while(GP3_bit);
                initialize();
            }
     }
}