XML Deserialization Error

Hi,

I am currently trying to test a web service:

PurchaseRequestCreateRequestConfirmation_In

From the Discovery system to a provider ERP system.

In the WSNavigator which is on the Discovery system, I entered values for the input parameters of the web service and clicked the "next" button. I got the following error:

"Error during deserialization of the SOAP reresponse on the client: XML Deserialization Error. XML is not valid. Element []<Item> is required in <n0:PurchaseRequestCreateConfirmation_sync> but can not be found."

Any Help will be appreciated.

Kind Regards'

David