Please excuse the question, but I do not want to take anything for granted.
When you purchase Premiere Elements 12, it comes with 2 discs, one for Windows and one for Mac.
Any chance that you picked up and are trying to use the Windows disc in the Mac computer?
If not, then try downloading tryout installation files for 12 from the following web site and then insert your purchased
serial number during installation.
Be sure to read and carry out carefully the web page's "Note: Very Important Instructions" otherwise you will end up with
an Access Denied message.
Please review, consider, and then let us know the outcome.
Add On...What Mac operating system are you using?