Not that the prop valve is bad, it is just that it may have air in it, either way it sounds like you have air in the system, just keep bleeding it out, follow the manufacturers procedure for bleeding, I think you start at the right rear wheel and then do the left rear, then right front and finally left front (furthest from master to closest to master)
Have someone help you so they can push the pedal while you open the bleeder. Make sure you have about 1 quart of DOT3 or DOT4 brake fluid to keep filling the resivoir up, don't let it go dry.