7683B not connecting

i have a 7683b injector that i am trying to hook up to a 6890+ when i plug it in and turn the power on the injector lights go green ready to run, and when i open and close the door the turret spins and syringe moves. but when i go to the gc to start a sequence the gc says no injector installed. i plugged a 7683a in and the unit picked up the injector immediately. any solutions?