Using an HTTP URI in XSLT's Document() function

[DancingRobot]

Hi there! I'm new. Anyways, I am having a problem with the document() function in XSLT. The document function works for me only when I use it to point to a local XML file like

<xsl:variable name="second_doc" select="document('second_doc.xml')"

but if I use an HTTP URI to point to an XML file like

<xsl:variable name="second_doc" select="document('http://myserver:7777/exist/rest/db/special/second_doc.xml')"

nothing is returned. Why isn't anything being returned?