Can't access dropdownlist in code behind

Question

I am new and learning ASP.Net webforms. I have a DropDownList here:

  <asp:DropDownList id="DropDownList1" runat="server">
  </asp:DropDownList>

I am trying to access it by typing "DropDownList1" in my Page_Load event. but Intellisense doesn't show DropDownList1. So I assume I am doing something wrong but don't understand what is wrong.

I'm trying to access DropDownList so I can programmatically populate it with numbers.

EDIT: if my dropdownlist is inside another control, then I'm not seeing it:

<%@ Page Title="Register" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="Register.aspx.cs" Inherits="Fake_Coupon_Site.Account.Register" %>

<asp:Content runat="server" ID="BodyContent" ContentPlaceHolderID="MainContent">
    <hgroup class="title">
        <h1><%: Title %>.</h1>
        <h2>Use the form below to create a new account.</h2>
        <h3><a href="http://stackoverflow.com/" title="Suggested reading">Suggested Reading</a>for <%= DateTime.Now.ToString("dddd, MMMM dd")%></h3>
    </hgroup>

    <asp:CreateUserWizard runat="server" ID="RegisterUser" ViewStateMode="Disabled" OnCreatedUser="RegisterUser_CreatedUser">
        <LayoutTemplate>
            <asp:PlaceHolder runat="server" ID="wizardStepPlaceholder" />
            <asp:PlaceHolder runat="server" ID="navigationPlaceholder" />
        </LayoutTemplate>
        <WizardSteps>
            <asp:CreateUserWizardStep runat="server" ID="RegisterUserWizardStep">
                <ContentTemplate>
                    <p class="message-info">
                        Passwords are required to be a minimum of <%: Membership.MinRequiredPasswordLength %> characters in length.
                    </p>

                    <p class="validation-summary-errors">
                        <asp:Literal runat="server" ID="ErrorMessage" />
                    </p>

                    <fieldset>
                        <legend>Registration Form</legend>
                        <ol>
                            <li>
                                <asp:Label runat="server" AssociatedControlID="UserName">User name</asp:Label>
                                <asp:TextBox runat="server" ID="UserName" />
                                <asp:RegularExpressionValidator runat="server" ControlToValidate="UserName" ValidationExpression=".{3,50}"
                                    CssClass="field-validation-error" ErrorMessage="The user name field needs to be 3 to 50 characters." />
                                <asp:RequiredFieldValidator runat="server" ControlToValidate="UserName" style="margin-left:-325px;"
                                    CssClass="field-validation-error" ErrorMessage="The user name field is required." />
                            </li>
                            <li>
                                <asp:Label runat="server" AssociatedControlID="Email">Email address</asp:Label>
                                <asp:TextBox runat="server" ID="Email" TextMode="Email" />
                                <asp:RequiredFieldValidator runat="server" ControlToValidate="Email"
                                    CssClass="field-validation-error" ErrorMessage="The email address field is required." />
                            </li>
                            <li>

                                <asp:DropDownList id="DropDownList1" runat="server">
                                </asp:DropDownList>

                            </li>

                            <li>
                                <asp:Label runat="server" AssociatedControlID="Password">Password</asp:Label>
                                <asp:TextBox runat="server" ID="Password" TextMode="Password" />
                                <asp:RequiredFieldValidator runat="server" ControlToValidate="Password"
                                    CssClass="field-validation-error" ErrorMessage="The password field is required." />
                            </li>
                            <li>
                                <asp:Label runat="server" AssociatedControlID="ConfirmPassword">Confirm password</asp:Label>
                                <asp:TextBox runat="server" ID="ConfirmPassword" TextMode="Password" />
                                <asp:RequiredFieldValidator runat="server" ControlToValidate="ConfirmPassword"
                                     CssClass="field-validation-error" Display="Dynamic" ErrorMessage="The confirm password field is required." />
                                <asp:CompareValidator runat="server" ControlToCompare="Password" ControlToValidate="ConfirmPassword"
                                     CssClass="field-validation-error" Display="Dynamic" ErrorMessage="The password and confirmation password do not match." />
                            </li>
                        </ol>
                        <asp:Button runat="server" CommandName="MoveNext" Text="Register" />
                    </fieldset>
                </ContentTemplate>
                <CustomNavigationTemplate />
            </asp:CreateUserWizardStep>
        </WizardSteps>
    </asp:CreateUserWizard>
</asp:Content>

Answer 1

What you need is this:

DropDownList DropDownList1 = (DropDownList)RegisterUserWizardStep.ContentTemplateContainer.FindControl("DropDownList1");

Answer 2

Since it's in a different NamingContainer than the Page you need to use FindControl to get it:

DropDownList DropDownList1= (DropDownList)RegisterUserWizardStep.FindControl("DropDownList1");