CSS not visible with XHTML decleration

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I have a page (valid by w3c, for CSS and XHTML), but when it has the
xml/XHTML/html decleration, the CSS doesn't work.  (FF1507Win98)

<?xml version="1.0" encoding="UTF-8"?>
 "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd ">
<html xmlns="http://www.w3.org/1999/xhtml " xml:lang="en">
<link rel="stylesheet" type="text/css" title="Blue and Orange"
href="page.css" />
...close head, body with div elements...
...end html...

I'm working on my local server (Apache 2.0.59, with PHP 5).

When the xml/XHTML/html decleration is replaced by just "<html>", the
css is loaded, and renders perfectly.

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