Problems with progressbar and backgroundworkerin windows application

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C#

Hi, I am Yogesh Sharma. I am working with progressbar in Windows Forms using C#. I need to open a Corel Draw file(.cdr) from my C# code. It takes about 10 seconds to do this task, hence I want to use ProgressBar. I am trying it with BackgroundWorker. My C# code is as follows...

private void button1_Click(object sender, EventArgs e)
{
    progressBar1.Maximum = 100;
    progressBar1.Step = 1;
    progressBar1.Value = 0;
    backgroundWorker1.RunWorkerAsync();
    CorelDRAW.Application cdr = new CorelDRAW.Application();
    cdr.OpenDocument(@"d:\xxx.cdr", 1);
    cdr.AppWindow.WindowState = cdrWindowState.cdrWindowMaximized;
}

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    BackgroundWorker worker = sender as BackgroundWorker;

    for (int i = 1; i <= 10; i++)
    {
        // Perform a time consuming operation and report progress.
        System.Threading.Thread.Sleep(1000);
        worker.ReportProgress(i * 10);
    }
}

private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    progressBar1.Value = e.ProgressPercentage;
}

My problem is that when I click on button1, ProgressBar doesn'n show any progress. And when the task is completed(i:e cdr file gets opened), progressbar shows the full progress immediately. I need to show the progress during the process of opening cdr file.

Please help what I am missing here or what is wrong with my code?
Any help will be appreciated.