So I have an interesting problem...
I currently have the latest version (2.52) of world modes plugin on my server which is running minecraft version 1.1. I have many plugins, but the one that I believe that is conflicting with world modes is essentials.
Whenever I attempt to change a different players game mode to the opposite of the one they have, it will not work. It just says switched game mode to creative, but the had creative in the first place.
I am the owner of this server and I have permission to all commands that are on this server and I am still unable to change another players game mode.

Example:
So lets say we have a player called Bob. Bob currently has his game mode set to survival and I decide that I want to give him creative. So I open open up the chat and type /gm Bob 1 and the chat replies with "Bob's game mode is set to survival" or something along those lines.

Now I am able to change my game mode just fine by doing /gm.

Any help with this problem would be greatly appreciated!

I have not tested yet, but with Essentials the automatic gamemodes did not work. I just switched to CommandBook. It should work now, I'm guessing.