按钮事件未在更新面板中触发

Question

我正在处理上传功能，我在我的Updatepanel中有我的Fileupload控件。当用户点击上传按钮时，click事件应该触发插入。在我的代码中，我放置了所有的fileupload控件，按钮在updatepanel2.On中button3_click没有事件发生。

  <div>
        <asp:UpdatePanel ID="UpdatePanel2" runat="server">
    <ContentTemplate>
        <asp:Panel ID="Panel1" runat="server" CssClass="cpHeader">
            <asp:Label ID="Label1" runat="server" />
        </asp:Panel>

        <asp:Panel ID="Panel2" runat="server" CssClass="cpBody">
       <asp:Label ID="Label6" runat="server" Text="You have not specified a file" 
             Visible="False" ForeColor="#FF3300"></asp:Label>

   <br />

     <asp:FileUpload ID="FileUpload1" runat="server" Width="412px" />
         <br />
         <br />

    <asp:Button ID="Button3" runat="server" Text="Upload" OnClick="Button3_Click" />
     <asp:Button ID="Button4" runat="server" Text="Cancel" />
      <asp:Label ID="Label8" runat="server" ></asp:Label>
         <asp:Label ID="Label9" runat="server"></asp:Label>

        </asp:Panel>



   <cc1:CollapsiblePanelExtender ID="CollapsiblePanelExtender2" runat="server"  
                       TargetControlID="Panel2" ExpandControlID="panel1"
   Collapsed="true" TextLabelID="label1" CollapsedText="Click to UPload a File"                    
    ExpandedText=" Please Select file to Upload " CollapseControlID="Button4"

      CollapsedSize="0">

        </cc1:CollapsiblePanelExtender>

    </ContentTemplate>
    <Triggers>
    <asp:AsyncPostBackTrigger ControlID ="Button3" EventName ="Click" />
    </Triggers>
    </asp:UpdatePanel>
</div>

      My Code behind for Button3_Click.
      Protected Void Button3_click(object sender,eventargs e)
 {
      if (!IsPostBack)
    {
      Button3.Attributes.Add("OnClick", "MyOnButtonClick()");
     string filepath = "~/"+"Uploads/" +   
   Path.GetFileName(FileUpload1.PostedFile.FileName);
            string filename = Path.GetFileName(filepath);
       string strcon =   
    ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
     if (FileUpload1.HasFile)
  {
  string Viewname = string.Empty;
      using (SqlConnection scn = new SqlConnection(strcon))
       {

    foreach (GridViewRow gvrow in GridView1.Rows)
    {
        CheckBox check_box = (CheckBox)gvrow.FindControl("checkbox1");
        if (check_box != null)
        {
            if (check_box.Checked)
            {
               // perspective = GridView1.DataKeys[gvrow.RowIndex].Value.ToString();
                //Convert.ToString(gvrow.Cells[1].Text);
                perspective = Convert.ToString(gvrow.Cells[1].Text);
            }

            else
                using (SqlCommand csm = scn.CreateCommand())
                {
                    scn.Open();
                    SqlCommand cmd = new SqlCommand("Insert", scn);
                    cmd.CommandType = CommandType.StoredProcedure;
                    cmd.Parameters.Add("@Name", SqlDbType.NVarChar).Value = TextBox1.Text;

                    cmd.Parameters.Add("@View", SqlDbType.NVarChar).Value = Viewname;
                    //conn.Open();
                    cmd.ExecuteNonQuery();
                    scn.Close();
                    FileUpload1.SaveAs(Server.MapPath(filepath));
                    Label8.Text = "FileSuccessfully Uploaded !";



                }

        }
    }
}

} }