Q: Why does my apple mail keep asking for my password even when its correct?

I've read alot of the people's posts about the same issue. However, I have tried everything including disabling and renabling my gmail IMAP and POP in my web account, Resetting the gmail password itself, and deleting and resetting the mail account. I have two computers. A thirteen inch macbook pro retina dispaly, and a 15 inch macbook pro. It works on the macbook pro which has OSX lion cuz its retina display, but not on the osx mavericks that I just bought yesterday. ANy idea why? Please help.