Make sure you are using a 3.5mm mono mini-plug on each end like the manual states. If not, the trigger function won't work. The Processor is designed to output a DC voltage when demanded to the slave unit (7500). The demand usually is created when the processor starts. If I remember correctly the 7500 has to be in the "go" mode and then you connect the trigger cable. You could cycle the main switch on the back and then press the on/off switch on the front to see if the circuit is acting in reverse. Make sure the 5509 does not have some trigger setting that needs adjustment in the menu. I am not familiar with the 5509 so I am grasping at straws here. Try connecting a 12 volt DC source to the 7500 and see if it triggers correctly. Once the processor comes on the 7500 should click and then the orange light will turn to blue. Ready to go. When all this is done contact Outlaw. Scott will fix you up.