FIRST OFF-are you doing this with a friend or by yourself?

You might have drained out too much at a time and didnt refill it fast enough.

Bleed out the master cylinder...Get one person in the car, one person with a wrench on the master cylinder. Bleed each line quite a few time and make sure you keep filling the reservoir. If that doesnt fix it, your master cylinder could be bad.

-Ant.