I added this code--query doesn't fail, but , after more testing, I found that
if I changed the second record returned, it didn't work.
<InfoPathEventHandler(MatchPath:="/dfs:myFields/dfs:dataFields/d:Offload_Request/@LocationID", EventType:=InfoPathEventType.OnAfterChange)> _
        Public Sub Offload_Request_LocationID_attr_OnAfterChange(ByVal e As
DataDOMEvent)
            ' Write code here to restore the global state.
           
            If (e.IsUndoRedo) then
            ' An undo or redo operation has occurred and the DOM is read-only.
                Return
            End If

            ' A field change has occurred and the DOM is writable. Write code here to
respond
        ' to the changes.
        'If FacilityID changes, LocationOffloadCode should be changed to
Null, so sproc can reassign correct code
        Dim myLocationOffloadCode As IXMLDOMNode

        If e.Operation = "Insert" Then
           Try
              myLocationOffloadCode =
thisXDocument.DOM.selectSingleNode("/dfs:myFields/dfs:dataFields/d:Offload_Request/@LocationOffloadCode")
              myLocationOffloadCode.text = Nothing
           Catch ex As Exception
              MsgBox(ex.ToString)
           End Try
        End If
     End Sub