Philsford

I've got a 94 F150 2WD with a straight 6. The hydraulic clutch recently started fading while I would drive it. If I drove it very long, I would have to pump the clutch pedal in order to build pressure back up to shift. Today, I changed the master cylinder since it is a LOT easier to change than the slave cylinder. After installation, I have bled the clutch numerous times but get NO pressure at the pedal. I knew that changing the master cylinder may not fix it (because it could be the slave cylinder) but I certainly did not expect it to fail all together. Any thoughts on this? Could I have purchased a bad master cylinder?