audiovox ccs 100 will not work

I installed a ccs-100 in 1980 MGB with a V8, the engine has an after market electronic ignition system. I connected the blue wire to the negative coil terminal, installed the sensor coil and one magnet on the drive shaft(rear wheel drive) and set the dip switches correctly, I think. All I can get it to do is blip when the set button is pushed then nothing. Checked all the voltages at the vacuum module they are correct. So I am really open to suggestions please help. Thanks MarkThanks Mark

Check that the violet wire for the brake circuit has less than 10 ohms resistance to ground with the ignition off. Try disconnecting the tach wire. It may be picking up a signal it doesn't like.sparky