Nios II and interrupt problem

[AAlas3]

Hey guys, I am new to Nios system design and I am facing problem regarding interrupts, I wrote a code as specified in HAL API interrupt example in Nios II software handbook but when I activate interrupt the processor doesn't go to ISR but it just freeze and I couldn't get back to main function, above is a screenshot of my C code in eclipse.

I am using DE2-115 board