Bleeding Front Brakes Problem

I have fitted new rear brake cylinders, Shoes etc and a new master cylinder on my 1988 MK1 GTI cabby.
Rear brakes bleed OK, The problem is the front discs, no fluid comes out of the bleeds when I open them  :?
The front brakes work, I have jacked up the front to check. The cars pulls up as before the replacements.
What could be going on? I need to bleed the discs to reduce pedal travel and the slight spongy feel.U
Tried old way to bleed two people etc and using Gunson kit.

U sure the nipples are being opened enough? Gunson kit (connects to a tyre one yeah) should easily do it mate.....did mine last weekend and biggest issue was the bloomin bleed nipples being seized. Worked em loose using a plumbers blowtorch and some adjustable pliers. Worst case, take off the brake line and check it ok tio that point...then its def the calliper side of things. Good luck either way m8

Taken the nipples out completely with no joy.  I have not taken the flexibles off since they look likely to be difficult. I am assuming the fluid is getting to the cylinders since the brakes work. Thanks for your ideas jinsta

If they haven't been bled for years and years they can get bunged up. Remove nipple, place an old rag/towel over the hole and pump the pedal hard. A slug of gunge will shoot out and you can then bleed as per normal.

It could also be a kink in the rigid pipe somewhere.

Thanks guys, I will try the pumping tomorrow. The service record makes no reference to work on the brakes in the past. The bleeds dont work on either side. so I assume no kinks.