Dodge,No brake fluid is getting to the rear brakes

I have been trying to figure out why my rear brakes are not getting any brake fluid. This problem just occurred this week. I had to replace the master cylinder and also the front right caliper because someone put power steering fluid instead of brake fluid in the master cylinder. My van has an ABS system. Before mounting the master cylinder, I pressurized it. To try to gravity bleed the brakes, my friend and I put the van on level ground and all four bleeder valves opened at each wheel. However, we could not get any fluid to come out at the rear brakes. So we closed the rear bleeders and worke