I do not work in command Rev. 236th
What could be causing this?
 
does not matter that I'm in the group, and so my command will not work
 
Are you sure you enabled some plugins? By default MCServer has no commands, only plugins use commands
 
MCServer has one command by default. /coords
 
Ah true, that one should work no matter what

 It should be removed in later versions though...