Is the plug your using that goes into the radio a screw in type? The VX6 uses a screw in type plug for the microphone / headset. The part of the body of the plug that is closest to the pin has threads on it. It's designed that way to help with the waterproof nature of the VX6.
When I tried to plug in my generic plug (without the threads on the body) it would not go in far enough to make contact and would not communicate with the radio.
I trimmed the plastic on the body of the plug next to the pin of the plug with wire cutters to make it smaller. It still was not small enough to just push the plug in, but I could then screw it in far enough until it made contact. Then the computer would communicate with the radio and I could use Chirp after that.
Possibly that's what's going on with yours???
73 Stan K8LL NW Ohio, USA 10-10# 76801 FP# 3255 Propagation is our master . . . but sometimes the master is cruel!