ส่งตัวแปร จาก form 2 ไป form 3 ได้แล้วแต่ ตรง form load ไม่เจอตัวแปรอะครับ มือใหม่ครับ รบกวนหน่อยครับ

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

namespace WindowsFormsApplication5
{
    public partial class Form3 : Form
    {

        public string na;
        string passvalue1;

      
        public string passvalue
        {

            get { return na; }
            set { na = value; }
          
        }
             

        string filenamee = "prefix.txt";
      
              

        public Form3()
        {
              InitializeComponent();               
       

               richTextBox1.Text = string.Empty;
               string[] strArr = File.ReadAllLines(Application.StartupPath + @"\\config\\" + na + @"\\" + filenamee);
               StringBuilder sb = new StringBuilder();

               for (int i = 0; i < strArr.Length; i++)
               {

                   sb.AppendLine(strArr[i]);
               }


               richTextBox1.Text = sb.ToString();        
           
        }


   

        private void button1_Click(object sender, EventArgs e)
        {
           
         
        }

   

        private void label1_Click(object sender, EventArgs e)
        {

        }

        private void button2_Click(object sender, EventArgs e)
        {         
        
                      
    

        }

        private void richTextBox1_TextChanged(object sender, EventArgs e)
        {

         
        }

     



        public void button1_Click_1(object sender, EventArgs e)
        {
            MessageBox.Show(na);
      


            File.WriteAllText(Application.StartupPath + @"\config\" + na + @"\" + filenamee, String.Empty);
            foreach (string line in richTextBox1.Lines)
            {

                using (StreamWriter writer = new StreamWriter(Application.StartupPath + @"\config\" + na + @"\" + filenamee, true))
                 
                {

                    writer.WriteLine(line);
                }

            }
            MessageBox.Show("Save Complete");        
             }
            
       

     
         
    }
}