Why Can't I Activate Parallels?

I purchased an academic version of Parallels from the Parallels website and received my activation key through my school email address. When I enter my activation key to activate Parallels Desktop 6.0, it tells me that Parallels has been successfully activated and then immediately reverts back to the "Trial" addition. Each time I start up Parallels, it tells me that I have X number of days remaining on my trial and asks if I would like to activate Parallels. I again enter the activation key I was given (I've both copied and pasted it from the email sent to me AND typed the activation key in by hand - both end in the same result, a trial version) and again I get a trial version. How do I unlock the trial version? I have purchased a valid license.