I have copied the makro from microsoft site:
http://support.microsoft.com/kb/291320/sv

But when i tried to start it this message shows:
Run error number 9
Index is out interval.
This line shows in yellow :
iListCount = Sheets("Sheet1").Range("A1:A100").Rows.Count

Anyone who knows what the problem are?
I would be very grateful

The makro is
Sub DelDups_OneList()
Dim iListCount As Integer
Dim iCtr As Integer

' Turn off screen updating to speed up macro.
Application.ScreenUpdating = False

' Get count of records to search through.
iListCount = Sheets("Sheet1").Range("A1:A100").Rows.Count
Sheets("Sheet1").Range("A1").Select
' Loop until end of records.
Do Until ActiveCell = ""
' Loop through records.
For iCtr = 1 To iListCount
' Don't compare against yourself.
' To specify a different column, change 1 to the column number.
If ActiveCell.Row < Sheets("Sheet1").Cells(iCtr, 1).Row Then
' Do comparison of next record.
If ActiveCell.Value = Sheets("Sheet1").Cells(iCtr, 1).Value Then
' If match is true then delete row.
Sheets("Sheet1").Cells(iCtr, 1).Delete xlShiftUp
' Increment counter to account for deleted row.
iCtr = iCtr + 1
End If
End If
Next iCtr
' Go to next record.
ActiveCell.Offset(1, 0).Select
Loop
Application.ScreenUpdating = True
MsgBox "Done!"
End Sub