wince6.0系统下打开系统键盘（c#2008）

       需要用到wince系统的自带键盘，参考网上做了一个按钮事件 代码如下：

 public Form1()
        {
            InitializeComponent();
        }
        public static uint SIPF_OFF = 0x00;//软键盘关闭 
        public static uint SIPF_ON = 0x01;//软键盘打开 
        [DllImport("coredll.dll")]
        public extern static void SipShowIM(uint dwFlag);
        bool KeyBoardOn = true;
        private void button1_Click(object sender, EventArgs e)
        {

            if (KeyBoardOn)
            {
                SipShowIM(SIPF_ON);
                KeyBoardOn = false;
            }
            else
            {
                SipShowIM(SIPF_OFF);
                KeyBoardOn = true;
            }

        }