RunWorkerAsync wired but doesn't step into bw_DoWork

See more:

C#

It is very puzzling. I have two copies of a c# project. Exact same code in both. The only difference is one project has A.dll as a reference, the other has B.dll as a reference. Project A works fine, and bw_DoWork is executed. Project B: it does not stop at a breakpoint in bw_DoWork. I cleaned and rebuilt B.dll. I also cleaned the c# solution and rebuilt it. What possible cause would there be for such behavior? I have the DoWork wired uup with bw_DoWork. I've googled a lot but no help.
thanks,
sb

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

private BackgroundWorker bw = new BackgroundWorker();
public Form1(EccTask newTask)
{
    InitializeComponent();

    if (newTask == null)
    {
        textBox1.Text = "No task data";
        return;
    }

    NewTask = newTask;

    bw.WorkerSupportsCancellation = true;
    bw.WorkerReportsProgress = true;
    bw.DoWork += new DoWorkEventHandler(bw_DoWork);
    bw.ProgressChanged += new ProgressChangedEventHandler(bw_ProgressChanged);
    bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);



}

private void bw_DoWork(object sender, DoWorkEventArgs e)
        {
            
            BackgroundWorker worker = sender as BackgroundWorker
            ...
         }