Check to make sure that the wires going to the speakers are actually the ones going to the speakers. Cheap way is to get a 9V battery and touch the wires to the terminals, you should get a clicking sound from the speakers evry time you touch the terminals, If not, then those are the wires going to the amp. Then make sure you get a new VC and connect it properly. I have a hunch that the wires are not correct.
It possible you have a bad VC but I have never run into one myself after installing hundreds of them.
This is partially why I run a 4 conductor wire from the amp to the VC location and 2 conductor wires from the VC location to the speakers, I never get them mixed up.