I lost brakes in my truck i made it home ok and i changed all the brake lines to all 4 wheels when i tried to bleed the brakes no fluid will come out anyware so i tried bleeding the master cylinder and put it back on truck and tried again still nothing i took the lines off at the proportioning valve (bottom lines) and tried to vacum pump fluid out i got a little fluid from one line and nothing from the other now what do i do