Equivalent Classes in OWL

Hello,

Given the following ontology - when i ask a reasoner (pellet) for
equivalent classes of #GraphicSupport, it gives me:

#GraphicSupport, #TradingStatus, #Thing

Why is this so?

Thanks,
Luke


  <owl:Class rdf:about="http://luke#GraphicSupport" />
  <owl:Class rdf:about="http://luke#Colour">
    <rdfs:subClassOf>
      <owl:Class rdf:about="http://luke#GraphicSupport"/>
    </rdfs:subClassOf>
  </owl:Class>
  <owl:Class rdf:about="http://luke#BlackAndWhite">
    <owl:complementOf>
      <owl:Class rdf:about="http://luke#Colour"/>
    </owl:complementOf>
    <rdfs:subClassOf>
      <owl:Class rdf:about="http://luke#GraphicSupport"/>
    </rdfs:subClassOf>
  </owl:Class>

  <owl:Class rdf:about="http://luke#TradingStatus">
    <owl:unionOf rdf:parseType="Collection">
      <owl:Class rdf:about="http://luke#Open"/>
      <owl:Class rdf:about="http://luke#Close"/>
    </owl:unionOf>
  </owl:Class>

  <owl:Class rdf:about="http://luke#Close">
    <owl:complementOf>
      <owl:Class rdf:about="http://luke#Open"/>
    </owl:complementOf>
  </owl:Class>