Basic "run-time error 1004" problem

Hi.

I have opened a new excel workbook, and inserted an ActiveX command button. The command button is programmed in VB with the following code:

Private Sub CommandButton1_Click()
    Dim i
    i = 2
    Sheets("Sheet3").Activate
    ActiveSheet.Range(Cells(i, 1), Cells(i, 4)).Select
End Sub

This produces the error "Run-time error '1004': Application-defined or object-defined error". I need help on how to select a range of cells, on a different worksheet, while using a variable as part of the cell adress. Thanks very much in advance!