Hi Don:
Possibly you may personally recall this info, but I'm posting here to provide additional help resources for troubleshooting these types of scenarios.
AFAIK, when FSUIPC was released for FSX RTM
et seq, it was programmed to allow connections to the FS sub-system
only via SimConnect.
Thus, FSUIPC has become a 3rd party "front-end" for SimConnect in FSX and P3D, and continues to be a stand-alone application for FS2Kx.
IIRC, according to Pete Dowson, this was due to a requirement by ACES that
all such FS connections must take place via that method, although apparently one can have several numeric versions of SimConnect.DLLs installed and active at one time.
Certainly many may find the FSUIPC interface methods a preferable way to connect to a currently loaded and running version of FS, but, IIUC, FSUIPC will only work if a version of SimConnect required by that
current loaded and running version of FS is also installed and working properly.
http://forum.simflight.com/topic/45074-fsx-help-logging-simconnect/
http://forum.simflight.com/topic/44295-fsuipc4-on-fsx-and-firewalls-revised/
https://www.microsoft.com/Products/Games/FSInsider/tips/Pages/BlockItOrNot.aspx
[
EDITED]
So, IIUC, if the version of SimConnect required for the current version of FS that is loaded and running is
not present and/or
not working properly,
FSUIPC will
not be able to connect to FS either (because, AFAIK, it ultimately must also make its 'own' connection to FS ...
via SimConnect).
[
END_EDIT]
Hope this info helps those troubleshooting these types of FSUIPC and SimConnect issues.
GaryGB