Permissions problems

I recently started a bukkit server and got a few basic plugins. One of these plugins was PermissionsEx. My server is using 1.7.9 since the host I'm using doesn't have the 1.8 bukkit snapshots yet. I installed the 1.7.9 permissionsEx plugin and it seems to load when I start the server, but the permissions don't actually go through. Im not sure if this is a problem with the file or a problem with the installation of the plugin. Im using MCProHosting as my server host. If anyone has an idea of what might be going wrong, that would be a great help. I can explain with more detail if needed.