Possibly because you did not set MaxFileSize?

>Hi Yuir,
>
>>How did you "tried setting the DefaultExt"?
>
>I used o.DefaultExt="txt".
>
>>
>>Will this work for you?
>>
>>o = CreateObject("MSComDlg.CommonDialog")
>>o.Filter = "All Files (*.*)|*.*|Text Files(*.txt)|*.txt|Batch Files (*.bat)|*.bat"
>>o.FilterIndex = 2
>>o.MaxFileSize=40 && you must set this in your code anyway
>>o.ShowOpen
>
>This works great. Why did the method I tried produce the error?
>
>Regards,
>
>Mike