Passing null (?) when multiple method overloads exist

14.1 version of the Infragistics.Document.Excel.Workbook needs an extra parameter to call the Save method. The documentation says pass null for the second to parameter for the default behavior. Doing so will make the call ambiguous with another overload. Casting doesn't work. Any idea? Here are the two overloads. Save (character, Infragistics.Documents.Excel.WorkbookSaveOptions) Save (character, Infragistics.Documents.Core.Packaging.IPackageFactory) According to Infragistics, the original Save(character) should still be there, but it is currently not listed.