Do you have it wired the way the links I gave have it done? What size wire did you use to jumper the gm solenoid? Needs to be at least a 12 gauge from what I have read. Someone used a piece of copper tubing that they flattened and drilled holes in the end to fit the screws. The MADElectrical kit comes with a metal piece shaped to fit so you don't have to use wire.
Also, does it totally not crank at all? If it cranks even a little bit, this fix won't fix that problem.
What size battery cable do you have running from the battery to the solenoid, and solenoid to starter?