[Seaside] Problem with static css file

[Robert Schwarz]

Hello,
after switching from Squeak 3.10 to Squeak 4.1 my Seaside (2.8a)  
Application don't recognize static css files.

I'm starting HTTP Service with:

| ma seaside |
HttpService allInstancesDo: [:each | each stop. each unregister].
WAKomEncoded stop.
seaside := WAKomEncoded default.
ma := ModuleAssembly core.
ma serverRoot: FileDirectory default fullName.
ma alias: '/seaside' to: [ma addPlug: [:request | seaside process:  
request]].
ma documentRoot: FileDirectory default fullName.
ma directoryIndex: 'index.html index.htm'.
ma serveFiles.
(HttpService startOn: 8008 named: 'httpd') plug: ma rootModule

and use for WAComponent:

updateRoot: anHtmlRoot
	super updateRoot: anHtmlRoot.
	anHtmlRoot stylesheet url: '/gos.css'

My operating system is MacOSX 10.5.8. The same configuration works  
fine with Squeak 3.10 and Seaside 2.8. Any ideas what's going wrong?
Robert