(Using Excel 2000 under Windows 98)

I have created a 1-cell named range by selecting cell A1 on Sheet1 and then
typing the name "MyCell" (without the quotes) in the names Litsbox.
Thereafter, I have typed this code in the click event of a command button
located in another sheet (Sheet2):

Range(ThisWorkbook.Names("MyName")).Value = 100

When I click on the button I get error 1004. However, if the button is in
Sheet1 it works fine. So how do I have to MyCell in the first case?