Arducopter and QGroundControl

I just built a new 3d printed drone. I plug it in to update it and calibrate it. QGroundControl does not recognize it. I t just keeps saying “waiting for vehicle to connect”. Other ground control program recognize it so I know the board is ok. Any suggestions on how to get it to connect to Qgroundcontrol?

It’s not the fact of being 3d printed that is relevant here.

What is relevant is which Flight Controller, what QGC version (and platform) and what was the other GCS app