The Big red X in my C# windows application

Question

My grogram: 1.recieve the **qrcode **from scanner. 2.query coordinate data from mysql database by **qrcode ** 3.draw circle in the picturebox with coordinate data

But there is a error: the red x often appear, I've ever not found the solution.

I used this method, but it isn't useful.

pb.Invoke((MethodInvoker)(delegate
{
    pb.Image = bmp;
}));

So, is ther any method for it Thanks!!!