Asp .net CType(e.Item.Cells(2).Controls(0), TextBox) ----> Error: Out of bound

I am trying to put a edit button in the DataGrid, so when clicked would display a textbox to edit the record.

Here is the code:
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   Private Sub MyDG_EditCommand(ByVal source As Object, ByVal e As  System.Web.UI.WebControls.DataGridCommandEventArgs) Handles MyDG.EditCommand

        MyDG.EditItemIndex = e.Item.ItemIndex()
        MyDG.DataBind()

        Dim key As String = MyDG.DataKeys(e.Item.ItemIndex).ToString

        Dim CatName, CatImage, CatThumb, CatDesc As String
        Dim tb As TextBox


        tb = CType(e.Item.Cells(2).Controls(0), TextBox) 'Here is where I am getting ERROR
        CatName = tb.Text

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It gives me following ERROR:
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Specified argument was out of the range of valid values. Parameter name: index

Line 149:        tb = CType(e.Item.Cells(2).Controls(0), TextBox)
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I Debug the program and try to get the values and it gave me following result:

?e.item.cells.count  ----------------------> 6
?e.item.cells.controls.count -------------> 0      'I think here is the problem because it is zero

But I don't know what does it mean and how would I solve it.

Please Help !!!