Double piston extender

I have a problem with the double piston extender.
When put a piston on top of the other and turn it on when both pistons are connected only the top piston extends, the bottom one doesn't extend, only when power the bittom piston directly with a redstone torch it exrends but after i remove the redstone torch the piston retracts but doenst take the top pistons with it.
Note: the pistons are sticky pistobs