Volvo Clutch Problems

[TRex]

Hi- I have an 89 volvo 740 turbo, 5spd, of course. Recently, my clutch slave cylinder decided to break on me. I ordered a new one from my friendly neighborhood VIP. After I installed the part, and refilled the brake reservoir with the necessary dot 4 fluid, the part refused to build up pressure, even with subsequent pumping and using the air release on the cylinder itself. Please, can anyone tell me what might be going on...?