服务器端RadComboBox ItemTemplate中的访问控制

我使用RadComboBox进行多项选择，为此我在RadComboBoxItemTemplate中使用了复选框和隐藏字段，此RadComboBbox在一个网格内，我的标记如下

<asp:TemplateField HeaderText="RESPONSIBLE DEPARTMENT" HeaderStyle-HorizontalAlign="Left">
                                                <EditItemTemplate>
                                                    <telerik:RadComboBox TabIndex="2" ID="rcbDept" runat="server" EmptyMessage="--Select Department--"
                                                        AllowCustomText="true" EnableScreenBoundaryDetection="false" Width="100px" EnableTextSelection="false"
                                                        Filter="Contains" OnClientDropDownClosed="DropDownClosed" OnClientFocus="ClientFocus">
                                                        <ItemTemplate>
                                                            <asp:CheckBox runat="server" ID="chk1" onclick="onCheckBoxClick(this)" Text='<%# DataBinder.Eval(Container.DataItem, "dept_name") %>' />
                                                            <asp:HiddenField ID="hdnColumn" runat="server" />
                                                        </ItemTemplate>
                                                    </telerik:RadComboBox>
                                                </EditItemTemplate>
                                                <FooterTemplate>
                                                    <telerik:RadComboBox TabIndex="2" ID="rcbDept" runat="server" EmptyMessage="--Select Department--"
                                                        AllowCustomText="true" EnableScreenBoundaryDetection="false" Width="100px" EnableTextSelection="false"
                                                        Filter="Contains" OnClientLoad="GetControlId" OnClientDropDownClosed="DropDownClosed"
                                                        OnClientFocus="ClientFocus">
                                                        <ItemTemplate>
                                                            <asp:CheckBox runat="server" ID="chk1" onclick="onCheckBoxClick(this)" Text='<%# DataBinder.Eval(Container.DataItem, "dept_name") %>' />
                                                            <asp:HiddenField ID="hdnColumn" runat="server" />
                                                        </ItemTemplate>
                                                    </telerik:RadComboBox>
                                                </FooterTemplate>
                                                <ItemTemplate>
                                                    <%# Eval("dept_name")%>
                                                </ItemTemplate>
                                                <HeaderStyle HorizontalAlign="Left" Width="100px" />
                                                <ItemStyle HorizontalAlign="Left" Width="100px" />
                                                <FooterStyle HorizontalAlign="Left" Width="100px" />
                                            </asp:TemplateField>

该部分位于gridview的列标记中我无法访问服务器端Radcombobox项目模板的隐藏控制值任何帮助都是非常可观的。提前感谢！！！。。。。

 foreach (GridViewRow row in GridView1.Rows)
 {
     string _rcbDeptSelectedValue = 
     (row.FindControl("rcbDept") as RadComboBox).SelectedValue;
 }

GridViewRow row = GridView1.FooterRow;
    RadComboBox rcbDept = row.FindControl("rcbDept") as RadComboBox;
    foreach (RadComboBoxItem item in rcbDept.Items)
    {
        CheckBox chk1 = (CheckBox)item.FindControl("chk1");
        HiddenField hdnColumn = (HiddenField)item.FindControl("hdnColumn");
        if (chk1.Checked)
        {
            //Item checked
            string str = hdnColumn.Value;
            //Access hiddedn field vale here
        }
        else
        {
            //Item Unchecked
            string str = hdnColumn.Value;
            //Access hiddedn field vale here
        }
    }