They always seem to be a bear! Try compressing the slave manually, make sure the reservoir is full, then opening the bleeder. Keep it compressed and let fluid flow by gravity. Close the bleeder and release. Do this several times until you feel increasing resistance. Once you get a little slave movement with the pedal you can do the normal bleeding routine. Check the routing of the flexible hose so that small amounts of air can find it's way "upstream".
Some people have had success with a "mityvac" pump.