Purchased Photoshop Elements 11 but serial number refuses to work. How to activate it?

Approximately one year ago I received Photoshop Elements 11 as a gift. By that time I had a dell computer and installed it there. However, after purchasing a MacBook Pro, my serial number is failing to work anymore when i try to reinstall the software. I have tried contacting adobe multiple times; very disappointed in their 'support' and lack of answers. I am becoming agitated from the long wait for a response, and hope after this message, I will receive help soon.