Why C's simulator doesn't work?

Dear all:

I'm write a simply program to test C for NXP.
I only open timer 1 to use,Then i set a breakpoint in the interrupt,
But the interrupt never be break,I don't why?
Can anyone tell me why?
//************************************************
void interrupt(void) { if(Timer_bit) { if(Timer_bit) { Timer_bit=0; TimerH=(65536-time1_base)/256; TtimerL=(65536-time1_base)%256;

if(!(--A)) A=10; } }
} //
void main() { initial(); while(1) { ClearwatchGod(); r_cnt++; }
} //