the file of the URL below validates properly as xhtml1.1, the CSS as well, but clicking on the "check for validity" of CSS validator result page fails

http://validator.w3.org/check?uri=http://www.privasphere.org/extProtoType/m4
/index.en.html
works fine.
Clicking on the
http://jigsaw.w3.org/css-validator/validator?uri=http://www.privasphere.org/
extProtoType/m4/index.en.html link
however yields:
<<Please, validate your XML document first!

Line 1

Column 3>>

I found other xhtml1.0 Transition documents that were exactly the same as
mine in line 1 col 3 and do validate??

I searched the archives and found that I could add as line 2
<?xml version='1.0' encoding='ISO-8859-1'?>
and just before the
<meta http-equiv="Content-Style-Type" content="text/css" />
This unfortunately still didn't fix it, any idea what is wrong?