URL in XSL document() returning error

[xpack]

I have an XSL file that is transforming my Pictures XML file into small tiles, great! But I want to add a drop-down option at the top of the page that would allow me to select another album while on the pictures page. I am using the document() method to pull in the albums from another XML file, but an error is being returned:"Error while parsing "http://mydomain.com/app/albums/?org=markk". No data is available for the requested resource."...\[code\]<xsl:variable name="url" select="document('http://mydomain.com/app/albums/?org=markk')/albums"/> <form> <fieldset> <div class="control-group"> <div class="controls"> <select> <option>Choose Album</option> <xsl:for-each select="$url/album"> <option><xsl:value-of select="@name"/></option> </xsl:for-each> </select> </div> </div> </fieldset> </form>\[/code\]