I have read a number of forums, however none of the suggested solutions have remedied this issue. I have Designer ES 8.2, Reader 9.1 & Acrobat Extended 9.1. I run reader to show clients how an extended form will look when they opened in reader. has anybody resolved this issue?
I was having the same problem and you've probably found the solution by now. Anyway, I found that if I opened the file with Adobe Acrobat, then from the Form menu select Edit form in designer, the Preview PDF tab became available again.