i try to usert something with de enterprise.wsdl

i am getting the following error when i request the UPSERT operation

Does anybody knows where this is refering to / what goes wrong or what doe i have to give a value?

 THE REQUEST

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:urn="urn:enterprise.soap.sforce.com" xmlns:urn1="urn:sobject.enterprise.soap.sforce.com">
   <soapenv:Header>
      <urn:EmailHeader>
         <urn:triggerAutoResponseEmail></urn:triggerAutoResponseEmail>
         <urn:triggerOtherEmail></urn:triggerOtherEmail>
         <urn:triggerUserEmail></urn:triggerUserEmail>
      </urn:EmailHeader>
      <urn:DebuggingHeader>
         <urn:debugLevel></urn:debugLevel>
      </urn:DebuggingHeader>
      <urn:MruHeader>
         <urn:updateMru></urn:updateMru>
      </urn:MruHeader>
      <urn:AssignmentRuleHeader>
         <urn:assignmentRuleId></urn:assignmentRuleId>
         <urn:useDefaultRule></urn:useDefaultRule>
      </urn:AssignmentRuleHeader>
      <urn:SessionHeader>
         <urn:sessionId>fp6KrNsQwVjKNplTnn4CN2xd</urn:sessionId>
      </urn:SessionHeader>
   </soapenv:Header>
   <soapenv:Body>
      <urn:upsert>
        <urn:externalIDFieldName>mskey__c</urn:externalIDFieldName>
        <urn:sObjects xsi:type="NewRBScodes__c">
           <mskey__c>1</mskey__c>
           <Name>000002</Name>
           <rlcode__c>340</rlcode__c>
        </urn:sObjects>
      </urn:upsert>
   </soapenv:Body>
</soapenv:Envelope> 

THE RESPONSE

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
   <soapenv:Body>
      <soapenv:Fault>
         <faultcode>soapenv:Client</faultcode>
         <faultstring>'' is not a valid value for the enum 'LogType'</faultstring>
      </soapenv:Fault>
   </soapenv:Body>
</soapenv:Envelope>