Question Prison Server Help

Hi.

I'm working on a server that includes a prison world, and I have a problem where most of the blocks in the mine cant be broken by people who aren't ops. Its mostly the outer edge of the mine where people can break, the middle mostly cant be broken. You don't get a message like "HEY! You cannot break this here" It simply says nothing. Here are possible plugins that might be the issue.
Essentials
WorldGuard
MultiverseCore
MultiversePortals
MineResetLite
PrisonRanks
Thanks, and I hope you can help.