inconsystancy depowering pistons

i have a setup with redstone were the redstone is connecting 6 pistons on top of a pumpking on top of the piston all lying down in one direction of the 6 2 are retracting and 4 aren't.

in the screen shot show only two of the cobblestone extanded whyle it should be 6 this is due to pistons under the front row of redstone not retracting