Every second piston won't retract when redstone dust is deactivated.

Put the summary of the bug you're having here

What I expected to happen was...:
The pistons placed under blocks 2, 4, 6, 8, ect. would retract when redstone was deactivated, like what had happened when the pistons were placed under blocks 1, 3, 5, 7, ect.

What actually happened was...:
The pistons under blocks 2, 4, 6, 8, ect. remained extended.

Steps to Reproduce:
1. Build a straight line of cobblestone floating in the air . 
2. Place pistons under 2nd block, 4th block, 6th block, 8th block, ect. 
3. Lay redstone across the top of the cobblestone. 
4. Place lever on far side of cobblestone from pistons.
5. Flip lever on (pistons should extend)
6. Flip lever off (in my case, the pistons didn't retract like they should)