ASP.Net add postbacktrigger for usercontrol's element run-time

i have PlaceHolder in which i loads runtime some usercontrols.

<asp:UpdatePanel ID="UpdatePanel_Items" runat="server">
                        <ContentTemplate>   
                            <asp:PlaceHolder ID="PlaceHolder_Main" runat="server"></asp:PlaceHolder>
                        </ContentTemplate>

user control has element

<asp:LinkButton ID="LinkButton_AddToCart" runat="server" OnClick="LinkButton_AddToCart_Click" CausesValidation="false"></asp:LinkButton>

After adding user controls to placeholder, i need to add postback 开发者_如何转开发trigger for LinkButton_AddToCart in every user control . i tried this:

foreach (Control item in PlaceHolder_Main.Controls)
        {
            try
            {
                WUC_Rim wuc = (WUC_Rim)item;
                PostBackTrigger trigger = new PostBackTrigger();                    
                LinkButton lnk = wuc.GetLinkButton_AddToCart();
                trigger.ControlID = lnk.UniqueID;    
                UpdatePanel_Items.Triggers.Add(trigger);
            }
            catch 
            {

            }            
        }

but has an error

A control with ID 'ctl00$MainContent$ctl02$LinkButton_AddToCart' could not be found for the trigger in UpdatePanel 'UpdatePanel_Items'.

PostBack triggers should be registered directly with ScriptManager, try it like this:

ScriptManager.GetCurrent(this).RegisterPostBackControl(wuc.GetLinkButton_AddToCart());

(Of course if this code is not in your Page class, you must put reference to it instead of 'this')

Use this:

import postback url as same page

 <asp:ImageButton AlternateText='<%#Eval("JobLink") %>' runat="server" ID="ibtnExcel"
                                                        ImageUrl="~/images/excel-doc.PNG" Width="25" Height="25" Visible='<%#Eval("Visible") %>'
                                                        ToolTip="Export to excel sheet" OnClick="ExportToExcel" PostBackUrl="~/billing/BillingHome.aspx" />