Seeing your site doesn't help me diagnose it since I cannot see configuration nor what files are in what locations.
Are you sure you have this in user.config
<add key="mojoEditorConfigFileName" value="mojoCustomEditor.config"/>
as indicated in step 8 of the ReadMe.txt
and that the file mojoCustomEditor.config exits in the root.
make sure that setting is not in more than one place in user.config, if it is then the one closest to the bottom of the file wins.