1968 Tic toc tach problem

[Rglass55]

Trying to install an OER Tac in my 68 Camaro.  I put in new circuit board for the tach. It has two wires--one to the ignition and one to the minus side of the coil. With this hooked up, the car will not start. Take the wire off the coil, it will start.

When trying to start it with the tach hooked up, it will start temporarily for an instant when you let go of the key, but will not keep running. This is a standard 68 Camare, all original edition, completely stock everything. Does anyone out there know anything that can help me?

Thanks in advance!
Roger