Hi all In spite of repeated attempts at installing/reinstalling and applyong the advice in the Forum I still could not get the Jetstream to activate. I have asked PMDG for help as the last resort. In the meantime .. A signpost to solving the problem with activating the Jetstream was alsodiscovering that a problem had appeared with my registered copy of FSUIPC4. The error message lead to me investigating further and I came across this link written by Peter Dowson http://forums.simflight.com/viewtopic.php?f=54&t=67994 using regedit as he advised I reached the following item in the Windows Registry:- Computer\HKEY_CURRENT_USER\Software\Microsoft\WIndows\CurrentVersion\WinTrust\Trust Providers\\Software Publishing\REG_DWORD My value was 0x00063c00 which I reset to 0x00023c00 (146432), apparently the default, as suggested. When I reinstalled the Jetstream the activation screen appeared and all works perfectly now. Might be useful to somebody else and PMDG too. Rory

Holy cow, that's great. Thanks for the post.