Upgrade Windows 7 Home Premium on laptop to Windows 7 Ultimate through MSDN

"I've successfully upgraded win 7 starter (OEM) to Ultimate using an MSDN key which was generated in August 09...

initially I just wanted to upgrade my notebook from starter to pro (I don't need bit locker and other ultimate features)... so i've generated a pro retail key on MSDN today... upgrade failed... kept telling me the key was invalid..

not sure if it's to do with the pro vs ultimate or when the key was generated..."