http://blogs.msdn.com/b/eric_carter/archive/2005/05/09/415767.aspxWhen programming in C#--if you want to omit an optional parameter for a method in the Excel object model, you have to pass System.Type.Missing to the parameter: myExcelApp.MethodWithOptionalParameter(System.Type.Missing); When you want to omit anen-USTelligent Evolution Platform Developer Build (Build: 5.6.50428.7875)http://blogs.msdn.com/b/eric_carter/archive/2005/05/09/415767.aspx#415771Mon, 09 May 2005 19:58:29 GMT91d46819-8472-40ad-a661-2c78acb4018c:415771Erno de Weerd<div style="clear:both;"></div><img src="http://blogs.msdn.com/aggbug.aspx?PostID=415771" width="1" height="1">