User Key Data to delete Opportunity Contact

Hello,

  I am trying to delete opportunity & its child elements in CRMOD using web services.

While trying to delete the opportunity contact, I am getting an error message "

No user key can be used for the Integration Component instance 'Opportunity Contact'.(SBL-EAI-04397) "

following is the xml message I am using to delete the opportunity Contact:

<input> 

<InvOpptyContactDelete_Inp> <part xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="OpportunityWS_OpportunityDeleteChild_Input"> <OpportunityWS_OpportunityDeleteChild_Input xmlns:tns="urn:crmondemand/ws/opportunity/10/2004" xmlns="urn:crmondemand/ws/opportunity/10/2004"> <xsdLocal1:ListOfOpportunity xmlns:xsdLocal1="urn:/crmondemand/xml/opportunity"> <xsdLocal1:Opportunity> <xsdLocal1:OpportunityName>R-0000000006H-201011-7045</xsdLocal1:OpportunityName