[mikets]

Yes, I have constructors on both MyRobot and TrcRobot (sorry that I simplified too much and did not show them in my code example). I suspect about inheritance too. So if the undefined symbol means it could not find the constructor of TrcRobot, I am puzzled because it's there. I am going to cut everything non-essential out to isolate the problem tonight and see what it is really complaining.