Thread:Project:Support desk/collapsiblenav does not appear in new skin based on vector

MediaWiki 	1.16.4 PHP 	5.2.17 (cgi-fcgi) MySQL 	5.1.53-log

UsabilityInitiative (Version 0.1.1) 	(Version 80586) Vector (Version 0.2.0) 	(Version 80586)

i am setting up a new skin, which is based on the Vector-Skin. It's named VectorModified, i followed: Manual:Skinning/Vector but did not change $IP/resources/Resources.php, as in the discussion is written, that this step is not necessary.

Now to the problem: In my new skin the left navigation is not collapsing, in the default skin (vector) it is. If i replace the orginal main-ltr.css by the new one and use as skin the original vector (and not thr modified one), the navigation is collapsing with the appereance of the modified main-ltr.css.

So the issue is not some wrong code in the css-file.

How can i tell the media-wiki to approve the collapsiblenav on the skin VectorModified?

Thanks a lot!