Problem when I add Rad Ajax Panel

[Hamza]

Hello all :)

I add an ajax loading panel and ajax panel to my page, but when I run the page I got this message

The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

what can I do to avoid it ? 

thanks all : )

[Hamza]

here is my code

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="Registration.ascx.cs"
    Inherits="Pages_Controls_Courses_Registration" %>
<telerik:RadScriptManager ID="RadScriptManager1" runat="server">
</telerik:RadScriptManager>
<telerik:RadAjaxLoadingPanel ID="RadAjaxLoadingPanel1" runat="server" Skin="Default">
</telerik:RadAjaxLoadingPanel>
<telerik:RadAjaxPanel ID="RadAjaxPanel1" runat="server" Width="900px"
    HorizontalAlign="NotSet" LoadingPanelID="RadAjaxLoadingPanel1">
    <center>
        <div style="padding: 0 0 0 0; margin: 0 0 0 0; background-color: #7f0214;">
            <table cellpadding="0" cellspacing="0" style="width: 900px;">
                <tr>
                    <td colspan="2">
                        <asp:Image ID="imgheader" runat="server" ImageUrl="~/Pics/CoursesMaster/registrationheader.PNG" />
                    </td>
                </tr>
                <tr>
                    <td colspan="2">

                    </td>
                </tr>
                <tr>
                    <td colspan="2">
                        <telerik:RadComboBox ID="ddlmajor" runat="server" Skin="Default" OnClientSelectedIndexChanging="LoadCourses"
                            OnItemsRequested="RadComboBox1_ItemsRequested" ValidationGroup="registrationprosess796437tfvdjghd">
                        </telerik:RadComboBox>

                        <telerik:RadComboBox ID="ddlcoursename" runat="server" Width="250" OnClientSelectedIndexChanging="LoadDates"
                            OnClientItemsRequested="ItemsLoaded" OnItemsRequested="RadComboBox2_ItemsRequested"
                            ValidationGroup="registrationprosess796437tfvdjghd">
                        </telerik:RadComboBox>

                        <telerik:RadComboBox ID="ddldate" runat="server" OnClientItemsRequested="ItemsLoaded"
                            OnItemsRequested="RadComboBox3_ItemsRequested" ValidationGroup="registrationprosess796437tfvdjghd">
                        </telerik:RadComboBox>
                    </td>
                </tr>
                <tr>
                    <td colspan="2">

                        <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="ddlmajor"
                            ValidationGroup="registrationprosess796437tfvdjghd"></asp:RequiredFieldValidator>
                        <asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ControlToValidate="ddlcoursename"
                            ValidationGroup="registrationprosess796437tfvdjghd"></asp:RequiredFieldValidator>
                        <asp:RequiredFieldValidator ID="RequiredFieldValidator3" runat="server" ControlToValidate="ddldate"
                            ValidationGroup="registrationprosess796437tfvdjghd"></asp:RequiredFieldValidator>
                    </td>
                </tr>
                <tr>
                    <td>
                        <table cellpadding="0" cellspacing="0" style="width: 400px;">
                            <tr>
                                <td>
                                    <telerik:RadTextBox ID="txtmail" runat="server" EmptyMessage="Your Mail" LabelWidth="64px"
                                        Width="160px" Height="25px" ValidationGroup="loginvalidationgroup784326fhj">
                                    </telerik:RadTextBox>
                                </td>
                                <td>
                                    <telerik:RadTextBox ID="txtPassword" runat="server" EmptyMessage="Password" Height="25px"
                                        LabelWidth="64px" Width="160px" TextMode="Password" ValidationGroup="loginvalidationgroup784326fhj">
                                    </telerik:RadTextBox>
                                </td>
                                <td>
                                    <telerik:RadButton ID="btnlogin" runat="server" Text="Log In" Height="25px" OnClick="btnlogin_Click"
                                        ValidationGroup="loginvalidationgroup784326fhj">
                                    </telerik:RadButton>
                                </td>
                            </tr>
                        </table>
                    </td>
                    <td rowspan="5" style="width: 500px;">
                        <asp:Label ID="lblSummary" runat="server" ForeColor="White" CssClass="FontNormal"></asp:Label>
                    </td>
                </tr>
                <tr>
                    <td style="width: 400px;">
                         <asp:RequiredFieldValidator ID="RequiredFieldValidator4" runat="server" ControlToValidate="txtPassword"
                            ValidationGroup="loginvalidationgroup784326fhj"></asp:RequiredFieldValidator>
                        <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ControlToValidate="txtmail"
                            ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*" ValidationGroup="loginvalidationgroup784326fhj"></asp:RegularExpressionValidator>

                    </td>
                </tr>
                <tr>
                    <td style="width: 400px;">
                        <telerik:RadTextBox ID="txtnotes" runat="server" EmptyMessage="Write some notes here!"
                            LabelWidth="64px" MaxLength="2000" TextMode="MultiLine" Width="391px" Height="200px"
                            ValidationGroup="registrationprosess796437tfvdjghd">
                        </telerik:RadTextBox>
                    </td>
                </tr>
                <tr>
                    <td>

                    </td>
                </tr>
                <tr>
                    <td style="width: 400px;">
                        <telerik:RadButton ID="btnreview" runat="server" Text="Review" Width="190px" ValidationGroup="registrationprosess796437tfvdjghd"
                            OnClick="btnreview_Click">
                        </telerik:RadButton>

                        <telerik:RadButton ID="btnSubmitreg" runat="server" Text="Submit" Width="190px" ValidationGroup="registrationprosess796437tfvdjghd"
                            OnClick="btnSubmitreg_Click">
                        </telerik:RadButton>
                    </td>
                </tr>
                <tr>
                    <td colspan="2">

                    </td>
                </tr>
            </table>
        </div>
    </center>
</telerik:RadAjaxPanel>
<script type="text/javascript">
    var ddlcoursenamevar;
    var ddldatevar;

    function pageLoad() {
        ddlcoursenamevar = $find("<%= ddlcoursename.ClientID %>");
        ddldatevar = $find("<%= ddldate.ClientID %>");
    }

    function LoadCourses(sender, eventArgs) {
        var item = eventArgs.get_item();
        ddlcoursenamevar.set_text("Loading...");
        ddldatevar.clearSelection();

        if (item.get_index() > 0) {
            ddlcoursenamevar.requestItems(item.get_value(), false);
        }
        else {
            ddlcoursenamevar.set_text(" ");
            ddlcoursenamevar.clearItems();

            ddldatevar.set_text(" ");
            ddldatevar.clearItems();
        }
    }

    function LoadDates(sender, eventArgs) {
        var item = eventArgs.get_item();

        ddldatevar.set_text("Loading...");
        ddldatevar.requestItems(item.get_value(), false);
    }

    function ItemsLoaded(sender, eventArgs) {
        if (sender.get_items().get_count() > 0) {
            sender.set_text(sender.get_items().getItem(0).get_text());
            sender.get_items().getItem(0).highlight();
        }

        sender.showDropDown();
    }

    </script>

[Eyup]

Hello Hamza,

You will need to wrap your script declaration in either RadCodeBlock or RadScriptBlock in order to allow server and client script to work well together with AJAX updates. The described solution is demonstrated in the following help topic:
RadCodeBlock and RadScriptBlock Overview

All the best,
Eyup
the Telerik team