Trailer brakes not releasing

This problem is driving me nuts.when i hook my truck to my trailer and tap the brakes just slightly,my trailers brakes wount realese quickly.i had a friend come and hooked the same trailer with his truck but no problem at all.what might be the problem with my truck?? And when the brakes are stuck and i press on the brakes hard it just realeses the brakes.

 

I just hooked my truck to a diffrent trailer and its acting the same way.once i tap my brakes just slightly the brakes lights on both truck and trailer stays on and locks up the brakes.after like 45 seconds they release.i have tried basically everything i can think of and no luck.

 

I tested the the tractor protection valve and its working fine.its supplying air to the traliler and onces i unhook it and release the trailer emergency knob its poping out

 

Yes i have and with a diffrent trailer its still doing the same so i know the problem is on my tructor