Deleting Activity using Web Services

Hi,

 While trying to delete activity associated to a Contact using web services, I am getting the following error:

No rows retrieved corresponding to the business component 'Action'(SBL-EAI-04378)

The user has been granted permission to Delete any activity (new feature in R21). Following is the message sent across for deletion of Activity.

<Inv_DeleteActivity_Inp> 

-<part xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="ActivityDelete_Input"> -<ActivityDelete_Input xmlns:tns="urn:crmondemand/ws/ecbs/activity/10/2004" xmlns="urn:crmondemand/ws/ecbs/activity/10/2004"> -<xsdLocal1:ListOfActivity xmlns:xsdLocal1="urn:/crmondemand/xml/Activity/Data"> -<xsdLocal1:Activity> <xsdLocal1:Id>ALKA-1DNCOX</xsdLocal1:Id><xsdLocal1:PrimaryContactExternalSystemId>R-0000001ALZ1</xsdLocal1:PrimaryContactExternalSystemId><xsdLocal1:PrimaryContact>TEST TEST</xsdLocal1:PrimaryContact><xsdLocal1:Subject>Test Task</xsdLocal1:Subject><xsdLocal1:IntegrationId>ALKA-1DNCOX</xsdLocal1:IntegrationId></xsdLocal1:Activity></xsdLocal1:ListOfActivity><tns:LOVLanguageMode>LIC</tns:LOVLanguageMode><tns:ViewMode>Manager</tns:ViewMode><tns:Echo>False</tns:Echo></ActivityDelete_Input></part></Inv_DeleteActivity_Inp>