checkbox in gridview not fired

Hi Expert,

I am working on asp.net web form.
I designed a usercontrol. In the user control I added gridview.
I added checkbox in gridview. But the event chkOne_OnCheckedChanged is not fired after I clicked the checkbox.

Appreciated for your help!!

                    <asp:GridView ID="gvNewCust" runat="server" AutoGenerateColumns="false" DataKeyNames="HierarchyID" AllowPaging="true"
                        EnableViewState="false" HeaderStyle-CssClass="DQLabel" Width="771px" OnRowDataBound="gvNewCust_RowDataBound">
                        <AlternatingRowStyle BackColor="#CCCCCC" />
                        <Columns>
                             <asp:TemplateField HeaderText="Select">
                                <ItemTemplate>
                                     <asp:CheckBox ID="chkOne" Checked="false" runat="server"  OnCheckedChanged="chkOne_OnCheckedChanged"  AutoPostBack="true"/>
                                </ItemTemplate>
                            </asp:TemplateField>
                            <asp:BoundField DataField="HierarchyID" HeaderText="HierarchyID" SortExpression="HierarchyID" />
                            <asp:BoundField DataField="isDeleted" HeaderText="isDeleted" SortExpression="isDeleted" />
                            <asp:BoundField DataField="InsertTS" HeaderText="InsertTS" SortExpression="InsertTS" />
                            <asp:BoundField DataField="InsertUserID" HeaderText="InsertUserID" SortExpression="InsertUserID" />
                            <asp:BoundField DataField="HierarchyNo" HeaderText="HierarchyNo" SortExpression="HierarchyNo" />
                            <asp:BoundField DataField="HierarchyName" HeaderText="HierarchyName" SortExpression="HierarchyName" />
                            <asp:BoundField DataField="RootNodeID" HeaderText="RootNodeID" SortExpression="RootNodeID" />
                            <asp:BoundField DataField="IsDefault" HeaderText="IsDefault" SortExpression="IsDefault" />
                        </Columns>
                        <HeaderStyle CssClass="DQLabel" Font-Bold="True" Font-Size="Small" />
                       
                    </asp:GridView>




---------------------------------------------------------------------------------------
//the following is not fired

        protected void chkOne_OnCheckedChanged(object sender, EventArgs e)
        {
            CheckBox chk = (CheckBox)sender;
            GridViewRow row = (GridViewRow)chk.Parent.Parent;
        }