MSScriptControl.ScriptControl 用法问题

新建一个类
    public class MyTest
    {
        public MyTest()
        { text = ""; }
        private string text;
        public string MyText
        {
            get
            {
                return text;
            }
            set
            {
                text = value;
                MessageBox.Show(text);
            }
        }
    }然后我想在 MSScriptControl.ScriptControl中用
                MyTest mClass= new ss.MyTest();
                MSScriptControl.ScriptControl sc = new ScriptControlClass();
                sc.Language = "JavaScript";
                sc.AllowUI = true;
                sc.AddCode(textBox1.Text);                sc.AddObject("mClass", mClass, true); //到这提示 类型转换错误 
                object[] parameters = new Object[0];
                sc.Run("hello", ref parameters);