go with the clear plastic tube on the bleed nipple and suck it through, it works for me every time, of course you need to open the nipple and i find it works better if you hold the brake lever in. I have a piece of tube about 3 feet long so i just suck it with me mouth, not the most sensible way i know but you get used to the taste after a while . Mind it could just be that you have mixed some dot 4 with dot 3 or 5, as this would cause sponginess aledgedly.