1986 420sel Ignition problem

[mascwopdude]

I have a 1988 420sel, I am getting frustrated when I turn the key to start the car the radio comes on and lights come on as it should but it will not engage the started. I ran a wire to the starter and when I hit the rigged starter button I installed it starts with no problem. When I go to turn off the engine I turn the key and it shuts down as it should, So far I have replaced the starter, installed a new neutral switch changed the ignition module and still having this problem. Could it be the ignition switch itself ?? not sure any help would be appreciated it before I just junk this car, Thanks!!!!!!!!!!!!!!!!!