Hi Allan-
'Could not connect to flight sim' is always attributed to FSUIPC (at least in myAASv2).
A couple of things to have a look at. When you run FS there should be a menu entry for Modules->FSUIPC. Check to see if that is there. If not...look in your <FS Install Dir>\modules for fsuipc.dll.
Also, I don't think it will make any difference, the latest version of FSUIPC is 3.999z9. Make sure the installer points to where you installed FS at.
Also, maybe try the FS registry repair tool from Flight1 before re-installing FSUIPC.
http://www.flight1software.com/files/FS_Registry_Repair.exeGive that a try and let us know.