Sticky pistons not working properly

The pistons aren't fully working - they won't go back to their original position when pushed by another piston. When I make a stack of pistons and connect them all to a lever, turn the lever on and off, the pistons will not go back to the place where i spawned them - they will just float where they were pushed by the piston below or next to them.

(I'm using an Android LG Optimus L5)