My psp umd case is not reading?

k my psp isn't reading the game properly and I can't figure out why...it's not the psp because it reads all of my other games fine which means it's the umd but the problem is that it pops up on the game menu which means it's able to verify there is a game in there and it even knows what game it is however when I click on it to start running it it goes normally like any other game but after the psp sony entertainment sign fades it goes black and stays black as my psp makes funny clicking sounds almost as if it is trying to read it but can't any help would be appreciated.