customunboundcolumndata event not firing in DEVExpress gridview

I have been struggling with the below code snippet. "CustomUnboundColumnData" event is not firing.

 Protected Sub gvAlertReport_CustomUnboundColumnData(ByVal sender As Object, ByVal e As    DevExpress.Web.ASPxGridView.ASPxGridViewColumnDataEventArgs)
    If e.Column.FieldName = "Active" Then
        Dim val As String = e.Value
        Di开发者_开发技巧m img As New ImageButton()
        Select Case val
            Case "False"
                img.ImageUrl = "Images/gray_bell.png"
                img.Attributes.Add("", "")
            Case "True"
                img.ImageUrl = "Images/red_bell.png"
                img.Attributes.Add("", "")
            Case Else

        End Select
     End If
End Sub

Thanks in Advance..

The CustomUnboundColumnData event is only triggered if there is a column in the ASPxGridView which is designed as an Unbound Column. To learn how this can be done, please refer to the Unbound Columns Overview topic. Also, please make certain that the gvAlertReport_CustomUnboundColumnData is the actual event handler for the ASPxGridView.