2001 Honda cbr 600 f4i brake problems?

Im having prombems with my 2001 honda cbr 600 f4i, i recently changed out my rear set and now my brakes wont work, i tried bleeding them and still when i press down on the brake they wont lock my wheel at all. Any help would be greatly appreciated.Ok so it started out with me buying a new rear set becuase my old one cracked. I took off the one on my bike and replaced it with the new(used) one purchased off ebay. After that I tried riding down the street, attempting to hit the back brakes with no luck. I rode the bike back home and bleed the brakes some more. The brake pedel pushes all the way down but the back brakes will not close up. Should i try to keep bleeding them because I dont think there is a whole lot of brake fluid in the setup becuase when i did the work undoing the cables alot of fluid came out. If theres any thing else youll need to know to anwser the question, i will be glad to tell but thats whats going on right now.Thank you for all the help, i would be lost without yahoo anwsers.

need more info, are they spongy ?does the brake pedal go all the way to a stop ?Suggestions are;A) You didnt get all of the air out (Bleed more)B) You mech put something together wrongC)You got dirt in with the cyclinder.you didnt give enough for better answers. If you need more help repost question

Master Cylinder malfunction.No,,it doesnt happen spontaneously.During entire life of the pads you changed,,,the Master Cylinder Piston Stroke was very SHORT.Only a Fraction of it's Full Stroke.All that time,,sediment,corrosion has been building up in the NON-Swept far end of the M/C Bore.When You started Bleeding it,,,,,You began stroking the M/C Piston FULL STROKE for 1st time in a LONG time.Scraping the Seals on the"Unpolished,Unused"section of Bore length.Jamming the piston into the"garbage pile",,,stirring up all the junk,,,,Forcing it into BOTH the Control Valve Seals And pushing the Disturbed, Now In-Solution Contaminants into the Brake Hose.When Cyl Piston RETRACTS,,,and that's IF it fully retracts,,,all that crap-laden fluid is clogging up the vent&refill ports in the valve .The system cannot Intake fresh Fluid from the reservoir to displace the air,,let alone pressurize the system and push Caliper Piston against Rotor..........................................Tak e Master Cylinder apart and Clean It,,,or install a rebuild kit.It's cheap and easy.Remove the brake hose and flush it THOROUGHLY.Not simply"good enough"to get Nice Clean Fluid Into it.But Good Enough to get the Injected Contaminants&Sediments OUT.Put it back together,,fill with Fresh Fluid,,Bleed It.Go lock'em up all ya want with your nice hard pedal...............................The Master Cylinder is the SOLE Device which Generates and Controls Pressure.When you Lose Pressure for No Obvious Reason,,The Reason becomes Obvious.Malfunction in the Pressure Pump or Control Valve.AKA,,,Master Cylinder.Good Luck---txm42