Problem with xerces2 J (cvc-elt.1: Cannot find the declaration of element)

Question

cvc-elt.1: Cannot find the declaration of element 'Unternehmen'.
Can anyone help me to get this problem solved?
I am using xerces to validate a xml with a xsd scheme and i think there must be a error within the scheme. But the XSD Validator on w3c.org says that the xsd is fine !? :-o
scheme (xsd)
<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
   <xsd:complexType name="PersonTyp" abstract="true">
     <xsd:sequence>
       <xsd:element name="Vorname" type="xsd:string" maxOccurs="3"/>
       <xsd:element name="Name" type="xsd:string"/>
       <xsd:element name="Geburtsdatum" type="xsd:date"/>
     </xsd:sequence>
   </xsd:complexType>
   <xsd:complexType name="MitarbeiterTyp">
     <xsd:complexContent>
       <xsd:extension base="PersonTyp">
         <xsd:sequence>
           <xsd:element name="Gehalt">
             <xsd:simpleType>
               <xsd:restriction base="xsd:float">
                 <xsd:minInclusive value="10000"/>
               </xsd:restriction>
             </xsd:simpleType>
           </xsd:element>
         </xsd:sequence>
       </xsd:extension>
     </xsd:complexContent>
   </xsd:complexType>
   <xsd:element name="Unternehmen">
     <xsd:complexType>
       <xsd:sequence>
         <xsd:element name="Mitarbeiter" type="MitarbeiterTyp"
           maxOccurs="unbounded"/>
       </xsd:sequence>
     </xsd:complexType>
   </xsd:element>
</xsd:schema>xml
<?xml version="1.0" encoding="UTF-8"?>
<Unternehmen xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:noNamespaceSchemaLocation="Beispiel.xsd">
<Mitarbeiter>
  <Vorname>Hagen</Vorname>
  <Vorname>Dieter</Vorname>
  <Name>Becker</Name>
  <Geburtsdatum>1967-08-13</Geburtsdatum>
  <Gehalt>39512.34</Gehalt>
</Mitarbeiter>
<Mitarbeiter>
  <Vorname>Jutta</Vorname>
  <Name>Stehl</Name>
  <Geburtsdatum>1976-09-11</Geburtsdatum>
  <Gehalt>42500.34</Gehalt>
</Mitarbeiter>
</Unternehmen>

Answer 1

forget about this thread.
i have read a chapter of http://java.sun.com/webservices/docs/1.2/tutorial/doc/index.html this document and found out that i missed a statement within my java code.
Next, you need to configure the parser factory to generate a parser that is namespace-aware parser, as well as validating:
  SAXParserFactory factory = SAXParserFactory.newInstance();
  factory.setNamespaceAware(true);
  factory.setValidating(true); I MISSED THE factory.setNamespaceAware(true); LINE!!!!