Mail is not downloading messages from two accounts but the messages are in the server.

Hello, I'm having this problem. Mail is not downloading messages from two accounts. I don't know why but there're two accounts working so bad. If I click with the right button on the account and click to see the account details, I can see the messages on the server but not in inbox. I made a sync with this account and my iphone and then the iphone downlad the messages with out problems. Not my imac at work or my imac at home... what can be wrong?

Thanks.