按组合框筛选RadGrid

我的问题是，当我尝试单击Radgrid中的组合框时，它什么都没做。

 <telerik:RadGrid ID="RadGrid" runat="server" DataSourceID="TestReleaseInformationSource" ShowStatusBar="true"
            OnItemCommand="RadGridItemCommand" OnPreRender="RadGrid_PreRender" AllowAutomaticUpdates="true" EnableLinqExpressions="false"
            AllowAutomaticDeletes="true" AllowPaging="true" AutoGenerateColumns="false" AllowFilteringByColumn="true">
            <MasterTableView DataKeyNames="PrimaryKey">
                <Columns>
                    <telerik:GridBoundColumn AllowFiltering="true" UniqueName="TeacherLastName" DataField="TeacherLastName" HeaderText="Last Name">
                        <FilterTemplate>
                            <telerik:RadComboBox ID="radComboBoxLastName" DataSourceID="TeacherLastNameDDL" DataTextField="TeacherLastName" DataValueField="TeacherLastName"
                                AppendDataBoundItems="true" SelectedValue='<%# ((GridItem)Container).OwnerTableView.GetColumn("TeacherLastName").CurrentFilterValue %>'
                                runat="server" OnClientSelectedIndexChanged="TeacherLastNameChanged">
                                <Items>
                                    <telerik:RadComboBoxItem Text="All" Selected="true" />
                                </Items>
                            </telerik:RadComboBox>
                            <telerik:RadScriptBlock ID="RadScriptBlock1" runat="server">
                                <script type="text/javascript">
                                    function TeacherLastNameChanged(sender, args)
                                    {
                                        var tableView = $find("<%# ((GridItem)Container).OwnerTableView.ClientID %>");
                                        tableView.filter("TeacherLastName", args.get_item().get_value(), "EqualTo");
                                    }
                                </script>
                            </telerik:RadScriptBlock>
                        </FilterTemplate>
                    </telerik:GridBoundColumn>

关于网格的预呈现

    protected void RadGrid_PreRender(object sender, EventArgs e)
    {
        if (RadGrid.EditItems.Count > 0)
        {
            GridNestedViewItem item = (GridNestedViewItem)RadGrid.MasterTableView.GetItems(GridItemType.NestedView)[Convert.ToInt32(RadGrid.EditIndexes[0])];
            item.Visible = false;
        }
        if (RadGrid.MasterTableView.FilterExpression != string.Empty)
        {
            RefreshCombos();
        }
    }
    protected void RefreshCombos()
    {
        TestReleaseInformationSource.SelectCommand = TestReleaseInformationSource.SelectCommand + " WHERE " + RadGrid.MasterTableView.FilterExpression.ToString();
        RadGrid.MasterTableView.Rebind();
    }

我已经看了好几个小时了，不知道问题出在哪里。任何想法都将不胜感激。如有必要，将发布更多代码。

我找到的一个解决方案是将组合框的RenderMode属性设置为本机。我仍然想要一个不同的变通方法。