Problem with document() function with external reference

Hello,

I have created one file xslt that modify an xml file. I take data by another 
external file, and for this I use the document function.
The problem is that for local  reference (for example document(c:\1.html) ) 
is ok, but when i use remote references, it doesn't find the page. In 
particular I am written this:

          <xsl:variable name="urilocale" select="document('c:\1.html')" />
           <xsl:copy-of select="$urilocale" />

While i want insert in parameter document something like:

//par[$numslide]/img/@longdesc

that contain the reference at web page: 
http://www.criad.unibo.it/mirrisil/videolecture/lecture1/video/imgSMIL/2.html
(but the page can change)

I hope that I have explained cleanly my problem. Thank you for attention

Bye bye