CSS Validator & CSS

Dear CSS Validator Team

I just made my first XHTML Page... (XHTML Strict) and wanted to validate
the CSS it contains... I'm almost sure, that I did all right (the XHTML
Validator confim's that) but the CSS Validator reports: 

org.xml.sax.SAXException: Please, fix your system identifier (URI) in
the DOCTYPE rule.

I don't know how current the CSS-Validator is.... but that's the URL

http://jigsaw.w3.org/css-validator/validator?uri=http%3A%2F%2Fwww.dominion.ch%2Findex.html&warning=1&profile=css2

The linkx I wanted to test is http://www.dominion.ch/index.html (it
contains some style="xxx" tags and I wanted to verify them... the .css I
linked works fine with the validator.

Can you please confirm, that the CSS Validator I used works with XHTML
and if so, can you please give me a small advise what I made wrong?

-- 
Thanks & Regards
Philipp Morger