Bleeding brake fluid. Not working! New master cylinder (bench bled) Two man brake bleeding not working?

OK so i bought a new master cylinder, bench bled it. installed it, topped off the fluid reservoir, left the cap open. Had someone pump and hold the brakes while i let the air purge out of the lines. We went on for about 10 minutes and still no fluid was coming out of the line. (I started with the line furthest from master cylinder(right rear).) The brake pedal wont build pressure, its spongy all the way to the bottom no matter how many times i pump.It is a 1986 Mercedes with abs. I don't know if the abs has anything to do with it. Help please anything!