Well.
Your pullets may not be used to feeding from a feeder. What do they do if you scatter it on the ground?
What do they do with straight wheat? (maize is a bit fattening for the summer, good in the winter when they need the warmth).
But i think the biggest issue is introduction of the pullets, which will have upset the pecking order. Taking out the 'bully' hen will do that too, personally I'd put her back and let them sort themselves out. This social unrest will have put them off their egg-laying stroke.
Are the new pullets healthy? Could they have introduced an illness? Did you worm them?
If yes to all of the above, I'd concentrate on providing them with plenty to do - straw to scratch about in, scatter your wheat in the straw, broccoli or cauliflower heads or millet sprays hung up to peck at, dig over a bit of the soil so they can hunt for worms. Find a couple of long branches to make into outdoor perches.
They'll sort out in good time.