Lpc2000

I'm running sample code from Rowley, using their "Crossworks for ARM" 
development suite. I'm working with IAR's demo board for the LPC2148 
and I'm having trouble with external interrupts. I have been able to 
run Rowley's timer_interrupt example, and have been able to stop at a 
set breakpoint in the startup.s file "irq_handler" section. But, I 
have not seen the external interrupt get that far. That being said, I 
have verified that the EXTINT flag is being set as it should be, when 
the external interrupt is asserted. Even though the flag is being set, 
it does not kickoff the irq_handler.

Any ideas what the problem could be?
P.S. I have used Rowley's timer_interrupt code as an example for my 
external interrupt code - they should act the same way, correct?...

Thanks!
Matt