[dotNetRDF-Support] Creating a class bug

[<c.c...@gm...>]

Hy,
i am building an ontolotgy. I would like create some classe inside.
this is my ontology

<?xml version="1.0"?>


<!DOCTYPE rdf:RDF [
    <!ENTITY owl "http://www.w3.org/2002/07/owl#" >
    <!ENTITY xsd "http://www.w3.org/2001/XMLSchema#" >
    <!ENTITY rdfs "http://www.w3.org/2000/01/rdf-schema#" >
    <!ENTITY rdf "http://www.w3.org/1999/02/22-rdf-syntax-ns#" >
    <!ENTITY RiconoscimentoDocumenti "http://www.semanticweb.org/Ac2/RiconoscimentoDocumenti#" >
]>


<rdf:RDF xmlns="http://www.w3.org/2002/07/owl#"
     xml:base="http://www.w3.org/2002/07/owl"
     xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
     xmlns:owl="http://www.w3.org/2002/07/owl#"
     xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
     xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
     xmlns:RiconoscimentoDocumenti="http://www.semanticweb.org/Ac2/RiconoscimentoDocumenti#">
    <Ontology rdf:about="http://www.semanticweb.org/Ac2/RiconoscimentoDocumenti"/>
    



    


    <!-- http://www.semanticweb.org/Ac2/RiconoscimentoDocumenti#Categoria -->

    <Class rdf:about="&RiconoscimentoDocumenti;Categoria">
        <rdfs:subClassOf rdf:resource="&RiconoscimentoDocumenti;Documenti"/>
    </Class>
    


    <!-- http://www.semanticweb.org/Ac2/RiconoscimentoDocumenti#Dictionary -->

    <Class rdf:about="&RiconoscimentoDocumenti;Dictionary"/>
    


    <!-- http://www.semanticweb.org/Ac2/RiconoscimentoDocumenti#DocumentToReconize -->

    <Class rdf:about="&RiconoscimentoDocumenti;DocumentToReconize">
        <rdfs:subClassOf rdf:resource="&RiconoscimentoDocumenti;Documenti"/>
    </Class>
    


    <!-- http://www.semanticweb.org/Ac2/RiconoscimentoDocumenti#Documenti -->

    <Class rdf:about="&RiconoscimentoDocumenti;Documenti"/>
</rdf:RDF>



<!-- Generated by the OWL API (version 3.4.2) http://owlapi.sourceforge.net –>

when i use the sintax to create a class 

OntologyGraph graph = new OntologyGraph();
OntologyClass class =  graph.CreateOntologyClass(new Uri(string uriClass));

Instead to obtain the tags of a class  i get the tags of a rdf description .
is there someone to know how to resolve this bug?

thanks to all.