Data binding issue on dropdownlist
===

I have a page that works fine when running from visual studio and installed on my machine.  However, once I install it on our server, the page will initially load fine but when the button is clicked, it just returns with a "URL was not found" error.

I have the issue tracked down to the data binding for the drop down list.  If I removed it, the page works fine on the server.

Any suggestions for what to look at on the server or in my code will be greatly appreciated.

My aspx

    <%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="SearchLandmarks.aspx.cs" Inherits="TripRequestPortal.SearchLandmarks" %>
    <asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server">
    </asp:Content>
    <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
    
        <div>
            <ajaxToolkit:ToolkitScriptManager ID="ToolkitScriptManagerSearchLandmarks" runat="server" />
            <asp:Label ID="lblCustomerNumber" runat="server" Visible="false" />
        </div>
    
        <div>
            <asp:CheckBox ID="chkBoxDateFrom" runat="server" />
            <asp:Label ID="lblDateFrom" runat="server" Text="Date From: " />
            <asp:TextBox ID="txtDateFrom" runat="server" />
            <asp:Image ID="imageDateFrom" runat="server" ImageUrl="~/Images/calendar_icon.jpg" />
            <ajaxToolkit:CalendarExtender ID="calendarExtenderDateFrom" runat="server" TargetControlID="txtDateFrom" Format="MM/dd/yyyy" PopupButtonID="imageDateFrom" />
            <ajaxToolkit:MaskedEditExtender ID="MaskedEditExtenderDateFrom" runat="server" TargetControlID="txtDateFrom" Mask="99/99/9999" MaskType="Date"/>
            <ajaxToolkit:MaskedEditValidator ID="MaskedEditValidatorDateFrom" runat="server" ControlToValidate="txtDateFrom" ControlExtender="MaskedEditExtenderDateFrom" IsValidEmpty="true" InvalidValueMessage="Inputted date not valid." EmptyValueMessage="Check box is checked so a date is required." />
        </div>
            
        <div>
            <asp:CheckBox ID="chkBoxOrigin" runat="server" />
            <asp:Label ID="lblOrigin" runat="server" Text="Label" />
            <asp:DropDownList ID="listOrigins" runat="server" DataSourceID="SqlDataSource1" 
                DataTextField="LANDMARKNAME" DataValueField="PRIKEY"  />
        </div>
    
        <div>
            <asp:Button ID="btnSearch" runat="server" Text="Search" 
                onclick="btnSearch_Click" />
        </div>
    
        <div>
            <asp:GridView ID="GridView1" runat="server">
            </asp:GridView>
            <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
                ConnectionString="<%$ ConnectionStrings:ConnectionStringTripStatus %>" 
                FilterExpression="customer='{0}'" 
                ProviderName="<%$ ConnectionStrings:ConnectionStringTripStatus.ProviderName %>" 
                SelectCommand="SELECT PRIKEY, CUSTOMER, CONCAT(CONCAT(LANDMARKNAME, ' | '), SITEID) AS LANDMARKNAME FROM LANDMARKS ORDER BY LANDMARKNAME">
                <FilterParameters>
                    <asp:ControlParameter ControlID="lblCustomerNumber" DefaultValue="-1" 
                        Name="newparameter" PropertyName="Text" />
                </FilterParameters>
            </asp:SqlDataSource>
        </div>
    
    </asp:Content>

my code behind

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Web;
    using System.Web.UI;
    using System.Web.UI.WebControls;
    
    namespace TripRequestPortal
    {
    	public partial class SearchLandmarks : System.Web.UI.Page
    	{
    		protected void Page_Load(object sender, EventArgs e)
    		{
                lblCustomerNumber.Text = "5";
    		}
    
            protected void btnSearch_Click(object sender, EventArgs e)
            {
                Response.Redirect("TripEntry.aspx");
            }
    	}
    }

Thanks