are you bleeding the correct way?
This is the way i use (may be incorrect but i have my reasons for doing so)
Start bleeding from the furthest brake caliper (left rear on R33). Loosen the bleeder, make sure the bleeder hose goes upwards (so you can see bubbles much easier), slowly depress the pedal, but not to the floor as you dont wanna ruin ur master, come up slowly, allow around 1-2 seconds for the new fluid. This is to make sure that the fluid is fully lubricating the seals. Keep depressing etc until u are happy with the new fluid coming out. Hold the pedal in the depressed position, lock the bleeder nipple, pump the pedal up (relatively quick short strokes) so you have a nice and firm pedal, then hold weight on the pedal, release the bleeder so it goes down about half way, lock bleeder then move onto the next one.
I think thats how I do it anyways