สอบถามการใช้ BackgroundWorker ใน C# Win App หน่อยครับ

private void button1_Click(object sender, EventArgs e)
        {
            if (backgroundWorker1.IsBusy != true)
            {
                backgroundWorker1.RunWorkerAsync();                
            }                      
        }

        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {                        
            for (int i = 1; i <= 10; i++)
                {
                   backgroundWorker1.ReportProgress(i);
                   Thread.Sleep(1000);
                }                     
        }

        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            label1.Text = e.ProgressPercentage.ToString() + "%";
        }

        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            label1.Text = "Complect";
        }

private void button1_Click(object sender, EventArgs e)
        {
            if (backgroundWorker1.IsBusy != true)
            {
                backgroundWorker1.RunWorkerAsync();                
            }
            
            
        }

        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {                
            Class1.Step(textBox4.Text, textBox1.Text, textBox8.Text, textBox2.Text, textBox3.Text,textBox5.Text,textBox6.Text,textBox7.Text);                          
        }

        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            label1.Text = "กำลังทำงาน";
             // ProgressChanged ไม่ทำงาน เด้งไปขั้นตอน RunWorkerCompleted เลย
        }

        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            label1.Text = "Complect";
        }