>I tested it with this code. Both returned -1.

I think it has to do with how the dataset is created. This is how I create it:

            oDataSet = New DataSet

            ' By default, .NET does not add the specific field length, which is needed in XML as at the other end
            ' someone would always get memo field instead of character field
            oDataAdapter.MissingSchemaAction = MissingSchemaAction.AddWithKey

            oDataAdapter.Fill(oDataSet)