You still have air in the system. It can be a booger to get it out sometimes. After many years of bleeding brakes with somebody operating the brake pedal I finally went to Motive Products and got a pressure bleeder.
The first time I used it, it was like I had died and gone to mechanic's heaven. Fill the pressure container his brake fluid attach the hose with it's adapter to your master cylinder pump it up and you can go to each bleed point and crank in open until all the bubbles come out and you are done, because of the brake fluid contained in the pressure tank you don't have to worry about running the master cylinder dry. Great for flushing and replacing your brake fluid as you should do every couple of years.