TextBox Mutiline&VerticalScrollBar

Hi, all;

I create a textbox and set the mutiline porperty as true;
and set scrollbars as ScrollBars.Vertical;
But I can not see the VerticalScroll bar?

why?
I use compactFramework, it says it supports two porperty

this is my source:

using System;
using System.Drawing;
using System.Collections;
using System.Windows.Forms;
using System.ComponentModel;
using System.Data;

namespace SmartDeviceApplication2
{
/// <summary>
/// Summary description for Form1.
/// </summary>
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.MainMenu mainMenu1;
public Form1()
{
//
// Required for Windows Form Designer support
//
InitializeComponent();

// Create an instance of a TextBox control.
TextBox textBox1 = new TextBox();
// Set the Multiline property to true.
textBox1.Multiline = true;
// Add vertical scroll bars to the TextBox control.
textBox1.ScrollBars = ScrollBars.Vertical;
// Allow the RETURN key to be entered in the TextBox control.
textBox1.AcceptsReturn = true;
// Allow the TAB key to be entered in the TextBox control.
textBox1.AcceptsTab = true;
// Set WordWrap to True to allow text to wrap to the next line.
textBox1.WordWrap = true;
// Set the default text of the control.
textBox1.Text = "Welcome!";
this.Controls.Add(textBox1);
// TODO: Add any constructor code after InitializeComponent call
//
}
/// <summary>
/// Clean up any resources being used.
/// </summary>
protected override void Dispose( bool disposing )
{
base.Dispose( disposing );
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.mainMenu1 = new System.Windows.Forms.MainMenu();
//
// Form1
//
this.Menu = this.mainMenu1;
this.Text = "Form1";
}
#endregion
/// <summary>
/// The main entry point for the application.
/// </summary>
static void Main()
{
Application.Run(new Form1());
}
}
}