Viewing Datasource Replacement

I am using a datasource for the first time. I have replaced a first, middle and last name with datasource values. I am getting an error on the following:

<soap:Detail>org.xml.sax.SAXParseException; cvc-pattern-valid: Value '' is not facet-valid with respect to pattern '([1-57-8][0-9]{2}|0([1-9][0-9]|[0-9][1-9])|6([0-57-9][0-9]|[0-9][0-57-9]))([1-9][0-9]|[0-9][1-9])([1-9]\d{3}|\d[1-9]\d{2}|\d{2}[1-9]\d|\d{3}[1-9])' for type 'null'.</soap:Detail>


So it looks to me like no value is being passed. Is there a way for me to see the request with the values from the datasource ?

Thanks