how to debug interrupt routine in proteus bug in proteus or i am mistaken

[aamir]

I am using microcontroller(PIC and AVR) AND WRITE SIMPLE routine which monitor external interrupt.INT pin of microcontroler is connected with simple push button program works well in normal running but when i debug inside proteus (with loading COF file) when programm waiting for interrupt and i press push button nothing happens ie program is not interrupted and debugger not goes to inteerupt routine.Also i have notified that when i push button when debuuger is running nothing changing to state of INT pin of microcontroller  while push button changing it state is it is proteus bug or any thing else . I am using proteus 7.6 sp4 from this forum O.S is windows xp sp3