Why isnt WMP changing my mp3 id tags anymore?

when i choose to select a new album for a song so that it can update the id tag i just does not change it. it leaves it as if i didnt do anything at all. also sometimes it chooses some albums that i just dont want so when i try to put another one it changes it but then it goes back to the same old choice it used to have. how can i fix this pls help. thanks