Sales order line delete fails for treetype=S line items

Question

SBO v8.8 PL17
In a Windows Console DI application, I need to delete lines that have TreeType=S from a Sales Order.
I get an error message that the Delete Line Failed and no other details for the error.
I have no trouble deleting the line in the SBO client sales order screen.
Often, the Sales Bill of Materials (SBOM) for the item on the SO line has changed after the line was created. 
Could the DI be validating the child item rows (treetype=I) for the father item against the current lines in the SBOM and blocking the deletion because they no longer match? 
In any case, how can I get around it or at least find out the actual reason the the line deletion fails?

Answer 1

Is the error description the same when you use old-school error checking?
                     If FixSO.GetByKey(DocEntry) Then
                         FixSO.Lines.SetCurrentLine(LineNum)
                         Try
                             FixSO.Lines.Delete()
                             tst = FixSO.Update
                             If tst <> 0 Then
                                 Dim errCode As Integer = 0
                                 Dim errMsg As String = String.Empty
                                 oCompany.GetLastError(errCode, errMsg)
                                 Console.WriteLine(errCode & " " & errMsg)
                             End If                   
                         Catch ex As Exception
                             Status = ex.Message & vbCrLf & oCompany.GetLastErrorDescription
                             Console.WriteLine(Status)
                         End Try
                     End If