Plugin Help PEX permissions yaml file

My server currently has spigot with two plugins installed, RTP, Vault and PEX, downloaded from the pages I linked to.

Here are my permissions: http://pastebin.com/j8JYR3QW. As you can see, I don't want privates to build, but they may use /rtp. Bozers can modify the world, while inheriting the ability to teleport. The admin gets access to everything.
Here are my issues:
1) The chat prefixes don't work.
2) Privates can modify the world. I don't know much about the modifyworld permission, but from the wiki I've read that it controls sprinting, placing blocks, using items, breaking blocks, killing entities, etc. I could use build: 'false', but that just denies build.
4) I suspect something is wrong with the permissions file.

PEX does not appear red in /plugins. Does anyone know what's wrong?