Bleeding Clutch with Syringe

[m4tti]

Tried bleeding my clutch last night. Ive previously done this with a syringe on brakes and clutches on other cars, but for some reason cannot pull solid fluid from the bleed nipple. I can get solid fluid pumping the peddle into the vacuum but not the other way round. I get loads of fine air bubbles. I did see a small drip of fluid on the bottom point of some threads on the underside of the master cylinder where the piston rod goes in.

Am wondering whether the draw of the syringe is so strong its showing up a duff seal. Has anyone else done a vacuum type bleed on their clutch. The other possibility is that air is getting in around the tubing on the bleed nipple.