External Interrupt (INT0) (Atkins)

I am using a PIC24HJ64GP502 with a MMA8452Q accelerometer (which uses I2C) to detect motion. I am using the Bully Bootloader in conjunction with MPLAB IDE v8.7. I cannot get the PIC INT0 (pin# 16) to activate its ISR when it receives a 3.3 V signal lastin..