If you are trying to bleesd a magura disc brake with a syringe as with the HS33 than this will not work. Disc brakes with a resivoir such as Hope, Magura and Grimeca then you bleed it in the same way as a motorbike disc by- 
 
1) Remove the top cap from the resivoir 
2) Attach a hose to the bleed valve on the caliper 
3) Pump the lever about 5-10 times to build pressure, hold lever in and release the bleed valve about 1/4 of a turn.  
4) This should make oil and air bubbles come out continue process till the fluid coming out has no air bubbles in it ( you have to keep an eye on the oil level in the resivoir top it up with what it recomends it usually says on  the lever) 
 
Trev