How to retrieve data ?

Hi all,

I have some trouble to retrieve data from an RDF file. The structure of my
RDF looks like this:

<?xml version="1.0"?>
<!DOCTYPE overlay SYSTEM "chrome://foxguardian/locale/foxguardian.dtd">
<RDF:RDF xmlns:RDF="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
	xmlns:MYINFOS="http://www.myurl.com/rdf#">
	
<RDF:Seq RDF:about="http://www.myurl.com/myinfos">
	<RDF:li>
	<RDF:Description about="http://www.myurl.com/myinfos/ADMIN">
		<MYINFOS:name>ADMIN</MYINFOS:name>
		<MYINFOS:description>short description for admin</MYINFOS:description>
	</RDF:Description>
	</RDF:li>
	<RDF:li>
	<RDF:Description about="http://www.myurl.com/myinfos/USER">
		<MYINFOS:name>USER</MYINFOS:name>
		<MYINFOS:description>short description for user</MYINFOS:description>
	</RDF:Description>
	</RDF:li>
</RDF:Seq>
</RDF:RDF>

i have a JS function whith a string param which can be 'ADMIN' or 'USER'
and i want to retrieve the 'description' value.

My JS function looks like this :

function getDescription(usertype) {
  var rdfService = Components.classes["@mozilla.org/rdf/rdf-service;1"].
      getService(Components.interfaces.nsIRDFService);
 
  var infos =  rdfService.GetResource("http://www.myurl.com/myinfos/"+usertype);
 
  var desc = rdfService.GetResource("http://www.myurl.com/myinfos/description");
  
  var target = dsource.GetTarget(infos, desc, true);
 
  alert(target);
}
but target is always null. What's wrong ?

NB: dsource has been retrieve during onload event of my xul form


KDO