I have bled the clutch slave until there is no more air. And still do not

What is your question?

I have bled the clutch slave and still have no clutch .How can I tell if the master cylinder is the problem. There is a little clutch but not enough to drive it. Had this trble before but bleeding slave cured it .could the slave line have rust in it and what is the cost per part? THKS BEN 1989 yr