[Rdfapi-php-interest] Unbound Prefix

Hi!

I have exported rdf-data from a mediawiki into a xml-file. Now I try to
query by using the following query-statement:

SELECT ?userstory WHERE
{
?res  rdfs:label ?userstory
?res rdf:type ?type
?type rdfs:label "Kategorie:User Story" }

I get an error-message "Unbound prefix rdfs:". I have no clue why, because I
have an older version of RAP where this kind of statement works. I also
tried:

PREFIX rdfs:<http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdf:<http://www.w3.org/2000/01/rdf-schema#>
{
?res  rdfs:label ?userstory
?res rdf:type ?type
?type rdfs:label "Kategorie:User Story" }

But this doesn't work either.

In my php-code, i am doing like in the rap-docu was shown:

$base = $rdfFile;
$model = ModelFactory::getDefaultModel();
$model->load($base);
$model->sparqlQuery($query);

Someone an idea?
Thanks,
Marco