1973 Chevy Nova ignition coil

I have rebuilt the engine and an having problems with the wiring. I hooked up to brand new coil. 12 volts to (+) side of coil and distributor wire to (-) side of the coil. I'm getting 12 volts on both sides of the coil with ignition key on. However not getting any spark from secondary wire. What could be the problem. I have a wiring diagram for this year nova and it shows that the hot primary wire on (+), and the distributor and the starter wire going to the (-) side