Hi,
where the precius stone of protecion is placed the pistons have a bug: http://i.imgur.com/QvBhl.png
When there isn't power in redstone usually the pistons are retracted but with the pstone they aren't able to retract, the only way is remove the precius stone, how can I do?
Regards.

If the piston is itself not in a protected zone, and it is trying to extend into a protected zone, PS prevents this un order to prevent grief inside protected fields via pistons.

Make sure the piston itself is inside the field as well.