It usualy happens if you run WCL based application on unsupported stack. But currently it is very unusualy situation.
The other way to get this error is to run WCL based application on BroadComm stack. Even BroadComm has aquired WidComm they have 2 Bluetooth stack versions. One labled as BroadComm other one as WidComm. WCL supports WidComm stack only.
But more often situation when you can get this error is if you didn't redistribute wcl2wbt.dll. More details about wcl2wbt are availbale in this topic:
http://forum.btframework.com/index.php/topic,955.0.htmlAlso, take a look on this topic:
http://forum.btframework.com/index.php/topic,139.0.htmlMake sure that wcl2wbt.dll has the same version as WCL version.
For .NET edition: make sure that reference to WCL.DLL is valid. As soon as it has Copy Local property set to True it may not replace local copy of WCL.DLL in project build directories. That may cause the transport detection problem.