secondaries wont open

hi Guys,
Bolted a holley 750 vac/sec onto my 360 this week.
Motor has 268 cam and air gap inlet, 3.23 rear.
for some reason the secodaries wont open.
Ive checked everything e.g linkage, diaphram, fitted weakest (white) spring and removed the ball check thingy.
Still no evidence of secondaries opening and ive driven the car all over today including full throttle kick down, cruising, lugging up hils.
Nothing seems to open 'em
ideas welcome