Excel VBA - fill in-cell dropdown

I'm using this to loop 5 times to fill an in-cell dropdown.

Sub Add_Drop_Down_Menu_Selection()

    For i = 1 To 5
    
        With Selection.Validation
        .Add Type:=xlValidateList, AlertStyle:=xlValidAlertStop, Operator:=xlBetween, _
        Formula1:="MyData"
        .IgnoreBlank = True
        .InCellDropdown = True
        End With

    Next i

End Sub

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But I get Runtime error 1004.
It works fine for the 1st run through the loop. I want it to ADD more items until the loop ends.

Thanks!