no brakes!?!

[69mach351]

Hello, I would appreciate any help. I can not get the air out of the rear brake lines. I have a new master cylinder, and booster, and new rear cylinders. I put plastic over the master cylinder just to make sure that it is not leaking out the top. There are no visible leaks in the lines. The two things that in my opinion could be the broblem is dirty brake lines. Can dirty brake lines prevent the air from competely exiting the line? The other thing that I am not sure about it the new adjustable proportionig valve I bought. I have it centered, but I don't know if I put it on correctly. The two lines that go to the distribution block from the adjustable proportion valve; the one closest to the rear on the proportioning block goes "in" and the one that is nearer to the front of the dist. block, is connected to the "out" side of the adjustable p.v. Is this correct? I would appreciate any help, if anyone knows any other reasons why air is in my lines? Thank you...David