daylight sensor not working right/piston/redstone block

When I placed down a daylight sensor next to a piston, it worked like it was supposed to, but when I switched it to night the redstone signal was dead, but the piston was still powered. I then put a piston down, a daylight sensor next to it, a block of redstone on the piston, and a piston on the redstone block. The daylight sensor/redstone block/pistons were working, but when night came, the whole contraption acted like it was still powered.