ok- years ago i bought the boxed Version ofthe PMDG B737-800/900. I install everything. Open a Aerosoft Account. Give them the Serial Number and download the newest Version which is avaible. start the Computer again and try to install the downloaded 600/700 Version- impossible, because i get a Failere Message. Download Version 1.20.8396 for 800/900 before install 600/700 Version.