page doesnot autopostback on radio button

<asp:Panelid="panel_left"runat="server"Visible="false"><asp:UpdatePanelrunat="server"ID="UpdatePanel1"UpdateMode="Conditional"><Triggers><asp:AsyncPostBackTriggerControlID="rdbGVRow"/></Triggers><ContentTemplate><divclass="row"style="padding-top:10px;"><divclass="col-md-12"><divclass="table-responsive"style="border: thin; overflow-y: hidden;"><asp:GridViewID="grid_contact"runat="server"AutoGenerateColumns="False"DataKeyNames="C_ID"OnRowDataBound="gv1_RowDataBound"OnPageIndexChanging="grid_contact_PageIndexChanging"AllowPaging="true"PageSize="10"CssClass="table  table-bordered table-hover"AutoPostBack="true"><HeaderStyleCssClass="table-bordered table-hover"Height="10px"/><PagerStylecssClass="gridpager"HorizontalAlign="Center"/><Columns><asp:TemplateFieldHeaderText="Detail"ItemStyle-HorizontalAlign="Center"><ItemTemplate><asp:RadioButtonID="rdbGVRow"runat="server"OnCheckedChanged="radioChecked"AutoPostBack="true"/></ItemTemplate></asp:TemplateField> 
                                  <asp:TemplateFieldHeaderText="Name"><ItemTemplate><%#Eval("NAME")%><%#Eval("LNAME")%></ItemTemplate></asp:TemplateField> 
                                <asp:BoundFieldDataField="C_ID"HeaderText="Contact Id"SortExpression="C_ID"/><asp:BoundFieldDataField="TITLE"HeaderText="Job Title"SortExpression="JOB TITLE"/><asp:BoundFieldDataField="Added_on"HeaderText="Added On"/><asp:TemplateFieldHeaderText="Status"><ItemTemplate><divclass="label label-lg label-success"><%#Eval("STATUS")%></div></ItemTemplate></asp:TemplateField></Columns></asp:GridView></div></div></div></ContentTemplate></asp:UpdatePanel></asp:Panel>