If an application use Simconnect in the wrong way, it create problems to other modules if loaded before or after, look here on the FsInn FAQ, it's not something specific to FSDT:
http://faq.apollo3.com/ljames/fsinn/vatsim/faq/Addons (LevelD Aircraft, other Aircraft, panels and gauges, and Scenery) Fail when FSInn is installed(An FSX issue)
Move the FSCopilot entry to the bottom of the dll.xml file. To locate it, type this in the "Run" field of Windows Start Manu:
%appdata%\Microsoft\FSX
You may use this web utility for convenience in reordering your dll.xml file:
http://flightsim.apollo3.com/utils/dllxmlorder.pl