Have you tried going into Applications and launching it from there?
Also, where did you get your copy of Premiere Elements 12? Downloaded from Adobe, purchased in a box or purchased from the App Store.
A number of people have reported issues with the App Store version.
App store version. I was opening it from apps, but what I found is that it had automatically generated an alias, and that alias that was broken. I had to go into the Premier folder proper and click on the original icon, then it launched. Thanks for getting back to me.
Glad you're able to get it working, furchgott.