Pump spinning? Added enough fluid? If system was dry (running a P/S rack w/ no fluid) ur gonna haveta bleed the system by adding fluid, turning side to side to completely fill the rack before you will have anything in the reservoir.
1: make sure pump turns both ways, not locked in either direction
2: make sure belt has proper tension (or is there at all, just making sure)
3: add fluid, turn wheel with car running and see if your reservoir fills
4: double, triple, and 1234567890x's check and make sure its not leaking externally
5: no leaks?
Try that out and see what's up.