Can't Install Version 1.6.7

[MrWizard516]

I am currently running version 1.6.6a and when I try to "Upgrade" using the installer it tells me it cannot find version 1.6.6. This makes no sense. How am I supposed to install the upgrade if it doesn't see that I am running version 1.6.6a? Any help I can get with this would be most appreciated.