License Error

I have a license for the CS6 Master Collection from my school, Academy of Art University. I had to uninstall and reinstall Photoshop to get an extension to function, and when I put the license code in everything was fine. I opened Photoshop and was told that the license had been installed on the maximum two computers and I had to deactivate one. I only have it installed on my desktop, so that doesn't make any sense. Now Photoshop tells me that the code is invalid. When I called the school HelpDesk, I was told to contact you because the code they gave me is verified and legitimate. Please tell me how to fix this, I need Photoshop for my classes and will fail without a way to process and edit my photographs.

I am using an iMac with OS X 10.6.8, 3.06 GHz processor and 4 GB memory.

Thank you,

Amanda