Ive been having a run of bad luck with mopar orange box ignitions so i put an MSD 6A box in the car. ive double and triple checked my wiring and have the box grounded to the block, yet i still have the following problem:

when turning the car over, i get a brief run time of around 1 second, but when i let off the ignition switch to go from "start" to "on" the engine immediately dies. ive tested the box and coil and determined them to be putting out spark when jumped.
is it the box or maybe my ignition switch?