下面是一个关于UG二次开发的问题：先创建两点再创建一条直线
问题：怎样才能UG里才能掉用

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

using NXOpen;
using NXOpen.Utilities;
using NXOpen.UF;
using NXOpenUI;
using NXOpen.Features;


namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private Point3d p1;
        private Point3d p2;
        /// <summary>
        /// 选择第一点
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button1_Click(object sender, EventArgs e)
        {
             p1 = new Point3d(0,0,0);
        }
       /// <summary>
       /// 选择第二点
       /// </summary>
       /// <param name="sender"></param>
       /// <param name="e"></param>
        private void button2_Click(object sender, EventArgs e)
        {
            p2 = new Point3d(10, 10, 10);
        }
        /// <summary>
        /// 创建直线
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button3_Click(object sender, EventArgs e)
        {
           Session.GetSession().Parts.Work.Curves.CreateLine(p1,p2);   
        }
    }
}