Hi,
this post should be on the Mach4 General Discussion board, there it will get the most exposure and you will get the most help.
Having said that getting help when you have provided absolutely no information on your installation and setup is going to be hard
to find. Do you log on to the General Motors site and say 'my car doesn't go'....and leave it at that?
The title of your post suggests that you are using a motion controller that worked with Mach3? If so what motion controller?.
You need to be aware that there are about six manufacturers who are producing Mach4 ready motion controllers, without
one of those Mach4 will not work for you.
Craig