[G's Chop Shop]

I just finished installing an LS3 out of a 2012 camaro into a 68 chevy truck. I used a harness supplied by the customer. Harness is the original from the motor. This harness was sent to Fuel Injection specialties to get reworked. Installation went good until I find out that the plug for the pedal was too short to route into the truck. I call FIS to let them know my problem so they sold me an extension to reach the pedal. I hook it up, start it up and nothing......no throttle response.

Am I missing something? Should I try another pedal?