Why I don't get my new mail when I click on the Get Mail icon? I don't see any mail activity in the Activity window either.

I have Mail 7.0 on Mountain Lion and it's working well. The problem I'm seeing is forcing Mail to get new messages by clicking on the Get New Mail icon (envelope). Also, there's no Mail Actiivity showing as I click on the icon.

Mail does periodically check my mail every 30 minutes without a problem.

Any ideas?