Rebranding WordpressMU Logo's Not Working?

Hi,

I have installed all of the elements of this plug-in and whilst everything else seems to be working fine, the logo's I have updated are not showing?

I have not updated every logo, just the following 3: http://4.biz/wp-admin/images/logo.gif, http://4.biz/wp-admin/images/wordpress-logo.png & http://4.biz/wp-includes/images/wlw/wp-watermark.png.

I have not renamed them, and if you look at the address of the images you will see how they should look. However, they still show the old Wordpress logo's.

I think there must be something really simple that I have not done, but I cannot figure it out!

Please help!!