Rear brakes locking up

[84GNGary]

I just replace the rear cylinders and hose and the front calipers, hoses due to age. I also replaced the front pads due to one was cracked, the rear shoes still had plenty of meat on them. I did not have the rotors or drums cut because they looked good with no scoring. I just failed inspection because the rear brakes were locking up. I was able to put the drums on easily and I did not do much more adjusting to them. I think my problem is with the front not grabbing maybe due to air or the new pads not being worn in yet. Is there anything else it could be The braking system is stock and never had any problems before.

 

[Red Regal T]

Like you said, possibly front pads not seated in yet.

 

[84GNGary]

Just had the rotors cut down and bleed the fronts again, went out for a drive, then at low speed I jammed on the brakes the rear tires left skid marks but not the front. Could it be the proportional valve and is there any way of checking it? Also what is the stem that comes out the front of the valve for and would moving it effect it's operation