SelectedIndexChanged event not firing of RadComboBox in vb.net

<telerik:GridBoundColumn DataField="Event" HeaderText="Event" AllowFiltering="true" CurrentFilterFunction="EqualTo" ShowFilterIcon="false">
<FilterTemplate>
<telerik:RadComboBox ID="cmbEventType" runat="server"></telerik:RadComboBox>
</FilterTemplate>
</telerik:GridBoundColumn>


In Code Behind:

Protected Sub RadGrid1_ItemCreated(sender As Object, e As Telerik.Web.UI.GridItemEventArgs)
If TypeOf e.Item Is GridFilteringItem Then
Dim filterItem As GridFilteringItem = DirectCast(e.Item, GridFilteringItem)
Dim combo As RadComboBox = DirectCast(filterItem("ColumnUniqueName").FindControl("cmbEventType"), RadComboBox)
combo.DataSource = dtTable
combo.DataBind()
combo.AutoPostBack = True

combo.SelectedIndexChanged += New RadComboBoxSelectedIndexChangedEventHandler(combo_SelectedIndexChanged)
End If
End Sub

Private Sub combo_SelectedIndexChanged(ByVal sender As Object, ByVal e As RadComboBoxSelectedIndexChangedEventArgs)

End Sub


But in item created event "combo.SelectedIndexChanged += New RadComboBoxSelectedIndexChangedEventHandler(combo_SelectedIndexChanged)" it gives me error
please help me how to fire SelectedIndexChanged event of radcombobox.