Sounds as if it has no ground and two lives hence why the coil won't work, the green wire will be the earth and the black will be switched live, not sure what ignition system RST has, I am presuming you have a RST transplant? I don't know the RST ignition system but seem to remember they have an inducive module (Which is what the wire on the dizzy would be for) which then sends this signal onto a ESC module. Somehow you have got two lives I should think when ignition is switched off you have nothing? I would check the wiring.

Martin