Had an issue at the track this weekend after I did my burnout I backed up and hit the tap down button and the pedal dropped to the floor like its supposed to. I have it set at 2000 rpm for pre-staging and staging. so after I staged I hit the transbrake button and then let go of the button and it never came on the two step. I launch at 4800 rpm. the air bottle was full and I also have a air bottle solenoid that's hooked up to the ignition to shut the bottle off and on. after this had happened I went back to the pits and tried it five times and it worked every time.

What model delay box?

Mega 450

Mine did that once, it was the button.....

Check to see if there is any slop or movement between the cylinder and the cable. I’ve had it happen in the past where the cylinder would lay over to the side just enough that it would catch under the top of the carb. Once you let off the throttle, it wouldnfree itself and work as it should. Chased it for a while.

OK thanks I'll check for that.