89SP air brake wont release, all pressure gauges normal(115) front +rear

[Ed Gardels]

Went to storage today to bring bus home, and the brake knob wont push
in releasing the brakes. It feels like air pressue pushing back,
preventing me from pushing it in.All the pressures came up normal, both
front and rear gauges register 115.Step operates. Everything seems
normal. I put buss in reverse to back out of my space and it wont move.
then tried fwd, same result. If I add power in reverse it will try to
move. I tried and tried to press brake knob in but it wont go. When I
press brake pedel I here normal air release sounds.
Im not very experienced, am I doing something wrong? Any help would
be apprieated. Thanks in advance!!
Ed Gardels 89sp
Arlington Texas