Question Block-place deny but let pistons move block?

Hi,

I used essentialsx (protection/antibuild) + worldgaurd! for protecting the world!
i want to limit all players for placing block in hole world = rg flag <name> block-place deny!
but i let them build in prison mine! and they can! (Break block!)

But when i use block-place deny!
Pistons for work shop stop working! and they can't move block!
how do i let pistons move block but not a player in that area!?
Thank you!

Permissions:

Code:

 - essentials.spawn
    - essentials.build
    - -essentials.build.place.46
    - -essentials.build.place.326
    - -essentials.build.place.327
    - essentials.build.interact.sign
    - essentials.build.interact.70
    - chestcommands.open.kit.yml
    - AutoPickup.enabled
    - -bukkit.command.plugins
    - -bukkit.command.version
    - -bukkit.command.reload
    - -bukkit.command.timings