I am having some issues setting up a single stage of nitrous off a button, button controls trans brake as well.

I have the kit set up on an rpm window and timer from the output switch, after the button is released nitrous is activated after .25 seconds.

Launch retard pulls -6 degree after .25 seconds, total timing is 40, timing is 34 degrees while the kit is on.
First hit was fine, after I set up to do another hit the engine wouldn't get on the brake, it would spit and sputter. After I hit the button the launch retard was not set to return to total taming, I went back in and set the timing to return to 40 degrees after 5 seconds,( just working on launching right now).

I have to use the trans brake button to reverse, my question is how should I set up the wiring to allow reverse without setting of the launch retard?