I read above what to try to fix this problem, but my question is, why would it suddenly show up? I loaded the airplane just fine last night, nothing changed. Suddenly now I cannot select it from the menu? What is going on here?

and I tried to reinstall but am getting a validate error message, I guess my order was reset because I asked for a full version and the response I got 12 hours ago was that the link would be available shortly???? Please PMDG send me the new download link!