Couple of possible things to try that could possibly work because it sounds as though air's trapped.
Knock all the hoses, caliper and lever with something, handle of a screw driver etc, this helps to dislodge any air.
Make sure that when putting the top cap and diaphram on that it is rolled towards the pointy end, make sure fluid overflows so no air can get in.
Another thing to try could be lowering the lever below the level of the caliper, so the air rises, make sure the bleed nipple is the highest point and only undoing the bleed nipple the minimum amount needed for flluid (and air to come out).
I'm asuming all fittings are tight.
I found this worked well and got air rising out of the lever, was to keep the nipple closed and with something between the pistons squeezing the lever a couple of times then continue bleeding.
Final thing before 'closing' the system push the pistons flush to the caliper and make sure your calipers alined properly and your pads are centred over the disk properly (no movement from the disc when the pads contact)
Was a good day, if a bit slippy and muddy!! Thanks to Barbara for making it happen, especially the extra effort in changing the venue.
Was nice to see some new and old faces there.
Looking forward to the next season.