1995 pontiac trans am will not shift from park...PLEASE HELP?

I tried many things..I have taken it to a mechanic 3 times and it still will not work! The wierd thing is..when it refuses to shift from park, if I wait a day..it usually shifts again, but if I shift it will lock back up once I put it back into park. What could be causing this? PLEASE HELP~!
It went to the mechanic twice* Sorry - The first time the mechanic said it was something under the steering coluum. The second time the mechanic took it he said it shifted when he got it to his shop like normal, but he said he would check it out before letting us have it back, then he said it was a brake switch..but after he put a brake switch in the same thing happened..It has 93k miles and it ran perfect the first time the mechanic fixed it..
The first time it was repaired I had it for about 1-2 months without any problems at all. When I bought the car it was fairly hard to shift from park (It took sheer force to press the shift button in) But after I drove it 10-20 times it stopped being so hard to shift and just wouldn't shift at all - You could press the button in all the way but the shift lever wouldn't move. The same thing is happening now. Like I said above..If I wait a day to try and shift it again, IT WILL MOVE??! But then if I put it back in park..it won't
Also, If it shifts out of park it has ZERO trouble at all trying to shift to or from R, N, D, 1, 2, 3

even if it goes in other gears, the problem could still be in the transmission.
what i dont understand is how the mechanics arent able to diagnose it properly if youve taken it back 3 times.

i would get a second opinion.