Editor Area Not Displaying Custom CSS

HI all.

I created a custom CSS based on my mononbooks main CSS and set my FCKEditor (for MediaWiki)
to find it:

FCKConfig.EditorAreaCSS = FCKConfig.BasePath + 'css/MWmonobooksmain.css' ;

Initially it loads but is quickly overwritten by another CSS a second later.
Can't seem to find where this secondary CSS is set.

Help....

Thanks,
Ebe