I`m using your TestApplication
I just entered some traces for debugging.
var brick = new Brick<Sensor,Sensor,Sensor,Sensor>(“usb”);
sbyte speed = 0;
it comes to tracing 3 and after throughs error (when I send command to MotorA)
I tried different motors and other commands, all the same.
Before I also had trouble like this http://www.monobrick.dk/forums/topic/fail-to-connect-ev3-via-usb/
But i fixed it the same way as posted there.