C#-Windows: Backgroundworke r

[Plater]

So it occured to me that I told people to use this to solve some thread-safeing issues, but that I had not been using it myself (I had been using a delegate with invokerequired which seemed to lock up program on closing)

Anyway, I've been using the example on msdn for using backgroundworke r to do async stuff.
The problem is IT STILL claims to be making unsafe thread calls.

The setup for the backgroundworke r:

private BackgroundWorker backgroundWorker1 = new BackgroundWorker();
private void Form1_Load(object sender, EventArgs e)
{
    backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
    backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
}
 
void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    string n=e.Argument.ToString();
    //MessageBox.Show("DoWork: "+n); 
    e.Result = n;
 
}
 
void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    // First, handle the case where an exception was thrown.
    if (e.Error != null)
    {
        MessageBox.Show(e.Error.Message);
    }
    else if (e.Cancelled)
    {
        // Next, handle the case where the user canceled 
        // the operation.
        // Note that due to a race condition in 
        // the DoWork event handler, the Cancelled
        // flag may not have been set, even though
        // CancelAsync was called.
 
        //resultLabel.Text = "Canceled";
    }
    else
    {
        // Finally, handle the case where the operation 
        // succeeded.
 
        //resultLabel.Text = e.Result.ToString();
 
        string n = e.Result.ToString();
        tbResults.AppendText(n);
    }
}
 

the function that i call from various threads:

public void testit()
{
    backgroundWorker1.RunWorkerAsync("thread safe writing!");
}
 

It doesn't error, but the "success" case in the workcomplete function throws the unsafe thread operation. What gives microsoft?