Precious Stones Plugin - Chests and Doors [Help!!]

Hello,

I need help from anyone who has experience configuring this plugin correctly. At the moment, it does what I want it to do but two things:

1. People can still actually open chests although they cannot see the inventory. On other servers I have played on with pstones you couldn't open the chest at all in the first place so why are people able to open the chest? I have the prevent-use set to 'true'.

2. People can open doors. I'm assuming this is somehow linked to the above but I have no idea. How do I stop players interacting with doors?

An example pstone here:

- title: Small Protection
block: 21
radius: 8
custom-height: 11
price: 3000
limit: 15
public-block-details: true
prevent-fire: true
prevent-place: true
prevent-destroy: true
prevent-pvp: true
prevent-unprotectable: true
prevent-flow: false
prevent-use: true
welcome-message: true
farewell-message: true
protect-inventories: true
mixing-group: 1
hidable: false
mask-on-disabled: 80