Can't update iTunes 12.0.0 to current version

I'm trying to update to the latest version of iTunes. When I check in the App Store, it says no updates are available. When I go into iTunes 12.0.0.140 and click on "Check for Updates" I get an alert saying a new version of iTunes, 12.0.1, is available. When I click on "Download iTunes" in that box, it goes to the App Store which then says again that no updates are available.

Within the App Store, I've tried clicking on Store:Show All Software Updates, but that didn't help.

I am having this problem only on my Mac Pro. No such problem exists on my Macbook Pro, which is also running Yosemite.