75e15 warning light wont go off!!?

i have a iveco 75e15. havent had much luck with the brakes from day one. firstly the masters went and locked the whole lot solid. because of that it cracked the discs so they were changed.along with new pads. it went for a test a few months back and i changed the metal fluid pipes as they loked a bit rusty. all perfect to go for the test. after the test the poor old thing has sat until now (about 4 months). it lives in a shed so that does it the world of good. fired her up there and brake tanks filled up and she popped off at 12 on the air clock. but the warning light under the handbrake sign wont go off. any ideas ? ive been over it checking the obvious switches to do with the brakes.

wot you think?