I dunno anything about the C++ implementation, but I'll give my opinion on the lite-c portion.

The third argument should be NULLVECTOR [vector(0,0,0)] in the way your using it.
Just make sure that vMove is getting some data in it.
If it is, try making the c_move be "IGNORE_ME|IGNORE_YOU|GLIDE" and see if it
gets you moving, you feet may be 'stuck' in the ground.