PC Sand Patch - Gp38-2 Brake Won't Release

When I try and release the brakes the brake cylinder never never moves below 27psi. All switches are set correctly including cut off and MU. The image attached shows the state of the control stand and brake pressure stuck at 28. It only seems to be a problem in time table sessions. Scenarios appear to be correct.

 

Forget about it just worked out I was not setting the MU valve to lead was just light switches.