1992 GMC Sonoma master cylinder is new, I have no pedal after bench bleeding. What is the matter and what can I do to correct the problem? We replaced a piece of brake line that was leaking on rear brakes. Then proceeded to bleed line on rear brakes and no pedal. Would it be the accuator valve keeping the system from having a pedal? Thank you for your help. toolmansam@aol.com

Optional Information:
1992 GMC Sonoma 2.?

Already Tried:
bench bleeding and line bleeding