Trouble Validating my transitional xhtml with css

I have a XHTML 1.0 document, with doctype:
<!DOCTYPE html
     PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
     "DTD/xhtml1-transitional.dtd">

Which is a valid doctype but for some reason I get this error when I try
to validate my CSS.

Target: http://technologyreview.org:8080/index.en.shtml
org.xml.sax.SAXException: Please, fix your system identifier (URI) in
the DOCTYPE rule

If you can tell me why I can't validate my CSS I will be very grateful. 
Thanks.

-- 
      /'^'\                                  /'^'\
     ( o o )                                ( o o )
-oOOO--(_)--OOOo------------------------oOOO--(_)--OOOo----
                    Michael Petnuch
           http://www.technologyreview.org:8080
  .oooO     			            oooO
  (   )   Oooo. 			   (   )   Oooo
---\ (----(  )------------------------------\ (----(  )-----
    \_)    ) /                               \_)   ) /
          (_/                                     (_/

Received on Tuesday, 25 December 2001 21:25:17 UTC