Brake Bleeding Issues!

Yes one at a time. I even had a buddy come out last week to pump the brakes while i opened up the bleeders one at a time starting at rr,lr,rf then lf. I called inline tube they sent me some instructions on bleeding the proportioning valve by finding which side i have flow. I have flow at the front side. I attached test light to lead wire and positive side of battery like the instructions showed opened front bleeders bleed the light never went off like it suppose to. I have been at these brakes for some time. I bleed bleed. I bet i have went through $50 dollars of brake fluid. I have never had this type of problem before bleeding brakes. It acts like I have a restiction to the rear brakes. Maybe a stuck valve in the proportioning valve?