Why a checkbox in a gridview doesn't work?

I am binding a checkbox in gridview with a database field, which stores boolean value i.e. IsRejected. I am trying to make it real time, i.e. if i tick checkbox then it should put 1 in database or 0 , i have tried but no effect. Why ?

 <asp:UpdatePanel ID="UpdatePanel1" runat="server">

                                        <ContentTemplate>
                                            <div>
                                                <asp:GridView ID="grdvwRejectedEmployees" runat="server" AutoGenerateColumns="false" Width="100%"
                                             DataKeyNames="EdrID" CssClass="table table-hover table-striped  table-bordered"
                                             AllowPaging="true" AllowSorting="true">

                                          <Columns>
                                            <asp:BoundField DataField="EdrID" HeaderText="Edr ID" />
                                            <asp:BoundField DataField="EmployerName" HeaderText="Employer" />
                                            <asp:BoundField DataField="BranchName" HeaderText="Branch" />
                                            <asp:BoundField DataField="EmployeeUniqueID" HeaderText="EmployeeUniqueID" />
                                            <asp:BoundField DataField="EmployeeName" HeaderText="Employee Name" />
                                            <asp:BoundField DataField="PayStartDate" HeaderText="Pay Start Date" />
                                            <asp:BoundField DataField="PayEndDate" HeaderText="Pay End Date" />
                                            <asp:TemplateField HeaderStyle-CssClass="visible-desktop" ItemStyle-CssClass="visible-desktop">
                                                <ItemTemplate>
                                                    <asp:CheckBox ID="chkBoxIsRejection" runat="server" Text='<%# Bind("IsRejected") %>' />
                                                </ItemTemplate>
                                            </asp:TemplateField>
                                            <%--<asp:BoundField DataField="IsRejected" HeaderText="Is Rejected" />--%>
                                          </Columns>

                                        </asp:GridView>
                                            </div>
                                        </ContentTemplate>

                                    </asp:UpdatePanel>

.cs

if (!IsPostBack) 
        {

            if (Session["UserCredential"] != null)
            {
                ClsSystemUser user = (ClsSystemUser)Session["UserCredential"];
                ClsSystemUser obj = new ClsSystemUser();
                obj = obj.GetOrganizationName(user.Type_ID, user.OfficeID, user.SystemUserID);

                int usertypeid = user.Type_ID;


                if (usertypeid == 3)
                {
                    //UserTypeID.Text = "Branch";

                    ClsRejectedFiles RejFiles = new ClsRejectedFiles();
                    grdvwRejectedEmployees.DataSource = RejFiles.GetRejectedFiles("30411098037111", 3, 1);
                    grdvwRejectedEmployees.DataBind();

                }