Please advice

i'm having an issue with AjaxControlToolkit ModalPopupExtender. Tried a simple code that should update labels after pressing "Save" in modal popup. Now, the modal popup is shown, but after pressing save, page is not updated (labels values are the same).

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="ajaxToolkit" %>

<ajaxToolkit:ModalPopupExtender ID="mpe" runat="server"  TargetControlID="btn1" CancelControlID="btnCancel"
OkControlID="OKButton"
PopupControlID="ModalPanel"  />
      <div>
      Contact Information:
      <asp:Label ID="lblName" runat="server" Text="test" /><br />
      <asp:Label ID="lblEmail" runat="server" Text="email@test" /><br />
      <asp:Button ID="btn1" runat="server" Text="Edit" />
    </div>
    <asp:Panel ID="ModalPanel" runat="server" Width="500px" CssClass="mclass">
      Name: <asp:TextBox ID="tbName" runat="server" /><br />
      Email: <asp:TextBox ID="tbEmail" runat="server" /><br />
      <asp:Button ID="OKButton" runat="server" Text="Save" OnClick="SaveData"  CausesValidation="false" />
      <asp:Button ID="btnCancel" runat="server" Text="Cancel" />
    </asp:Panel>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

using mojoPortal.Web;
using mojoPortal.Web.UI;
using mojoPortal.Business;
using mojoPortal.Business.WebHelpers;
using mojoPortal.Business.WebHelpers.UserRegisteredHandlers;
using mojoPortal.Web.Configuration;
using mojoPortal.Web.Controls;
using mojoPortal.Web.Editor;
using mojoPortal.Web.Framework;
using Resources;
namespace Test.Features.UI.Secure.MyProfile
{
    public partial class customProfileTabs1 : SiteModuleControl
    {
        protected void SaveData(object sender, EventArgs e)
        {
            lblName.Text = HttpUtility.HtmlEncode(tbName.Text);
            lblEmail.Text = HttpUtility.HtmlEncode(tbEmail.Text);
        }
        protected void Page_Load(object sender, EventArgs e)
        {
          if (ScriptController != null)
                {
                    ScriptController.RegisterAsyncPostBackControl(OKButton);

                }

            if (!Page.IsPostBack)
            {
                tbName.Text = lblName.Text;
                tbEmail.Text = lblEmail.Text;
                           }

        }
    }
}