Coding for Option Buttons

I have three option buttons in a group box.

The code I tried (below) doesn't work, and I'd appreciate some advice, please.

Private Sub optListing_Click()
'If Cells(12, 1).Value = "True" Then
    Cells(21, 2).Value = Cells(14, 3).Value
    ...
End Sub
Private Sub optSell_Click()
'ElseIf Cells(13, 1).Value = "True" Then
    Cells(26, 2).Value = Cells(14, 3).Value
    ...
    End Sub
Private Sub optBoth_Click()
    Cells(21, 2).Value = Cells(14, 3).Value
    Cells(26, 2).Value = Cells(14, 3).Value
    ...
End If
End Sub