hi guys need a bit of help quickly if somebody would be kind enough to

im in the process of bleeding the brakes on the rear of my focus st170 ...

i have the resovoir cap of and a hose on the nipple of the rear shoe(one i have changed) and im pumping the pedal to get the air out but the pedal wont stiffen up even tho theres no longer air coming out any ideas?? what am i doing wrong?