CPP Rear Disc Brakes not bleeding!!

[Tx70Gmc]

I apologize if this has been discussed before, I have searched the forums and outside the forums with no luck.

I am currently trying to install the CPP Rear Disc Brake Conversion on my 70 C10.
I have the Ebrake adjusted properly and it works great, but I cant get fluid to come out of the bleeders.

In fact when I step on the brakes nothing happens, the pistons do not try to squeeze at all.
I have tried to bleed the rear brakes using gravity, vaccum, pushing the brake, etc. Without success.

I installed the Front CPP Disc Brake conversion and they work great.

I have the Wilwood master cylinder and booster with a Wilwood adjustable proportioning valve.

Anyway any help we be appreciated.

Thanks