Motor works OK all day long without VB. There is no one else using the same com port but me.
After loading VB, the motor responses one time and no more. I have to close both VB and Arduino sketches, then unplug USB
After that, I plug USB back, load VB and Arduino sketch. It works for one time and stops.
I think my VB program is the culprit.
Thanks for looking into it.