问带有asp.net注册表用户控件的下拉列表

EN

<asp:CreateUserWizard ID="RegisterUser" runat="server" EnableViewState="false"
                      CancelDestinationPageUrl="RegistrationFailed.aspx" DisableCreatedUser="true"
                      ContinueDestinationPageUrl="Login.aspx" LoginCreatedUser="false">
    <LayoutTemplate>
        <asp:PlaceHolder ID="wizardStepPlaceholder" runat="server"></asp:PlaceHolder>
        <asp:PlaceHolder ID="navigationPlaceholder" runat="server"></asp:PlaceHolder>
    </LayoutTemplate>
    <WizardSteps>
        <asp:CreateUserWizardStep ID="RegisterUserWizardStep" runat="server">
            <ContentTemplate>
                <span class="failureNotification">
                    <asp:Literal ID="ErrorMessage" runat="server"></asp:Literal>
                </span>
                <asp:ValidationSummary ID="RegisterUserValidationSummary" runat="server" CssClass="failureNotification" 
                     ValidationGroup="RegisterUserValidationGroup"/>
                <div class="accountInfo">
                    <fieldset class="register">
                        <legend>Account Information</legend>
                        'All other fields removed for brevity
                        <p>
                            <asp:Label ID="QuestionLabel" runat="server" AssociatedControlID="Question">Select Security Question:</asp:Label>
                            <asp:DropDownList ID="Question" runat="server">
                            </asp:DropDownList><br />
                            <i style="font-size: .7em;">If you forget your password you will be asked the security question you choose here and prompted to enter the answer you specify below.</i>
                            <asp:RequiredFieldValidator ID="rfvSecurityQuestion" runat="server" ControlToValidate="Question" 
                                 CssClass="failureNotification" ErrorMessage="&laquo; [Required]" ToolTip="A security question is required." 
                                 ValidationGroup="RegisterUserValidationGroup">*</asp:RequiredFieldValidator>     
                        </p>
                         <p>
                            <asp:Label ID="Answerlabel" runat="server" AssociatedControlID="Answer">Security Answer:</asp:Label>
                            <asp:TextBox ID="Answer" runat="server" CssClass="textEntry"></asp:TextBox>
                            <asp:RequiredFieldValidator ID="AnswerRequired" runat="server" ControlToValidate="Answer" 
                                 CssClass="failureNotification" ErrorMessage="&laquo; [Required]" ToolTip="Security answer is required." 
                                 ValidationGroup="RegisterUserValidationGroup">*</asp:RequiredFieldValidator>
                        </p>
                    </fieldset>
                    <p class="submitButton">
                        <asp:Button ID="CreateUserButton" runat="server" CommandName="MoveNext" Text="Create User" 
                             ValidationGroup="RegisterUserValidationGroup" CssClass="buttons" />
                    </p>
                </div>
            </ContentTemplate>
            <CustomNavigationTemplate>
            </CustomNavigationTemplate>
        </asp:CreateUserWizardStep>
    </WizardSteps>
</asp:CreateUserWizard>

 Protected Sub Page_PreLoad(sender As Object, e As EventArgs) Handles Me.PreLoad

        Dim ddl As DropDownList = TryCast(FindControl(RegisterUser.Question), DropDownList)
        'If ddl Is Nothing Then MsgBox("nothing") ' for testing if ddl is found
        'Dim itemlist As New List(Of String)
        'itemlist = GetSecurityQuestionsforDDL()
        'For Each item As String In itemlist
        ddl.Items.Add(New ListItem("did this get added?"))
        'Next

End Sub