图片框没有更新内容

抱歉我的英语不好…你好，我已经做了这个图片框，但每当我试图加载一个新的图像在那里，它不显示任何东西，只是一个空的图片框控件。这是我现在的代码:

var loadImage = new BackgroundWorker();
loadImage.RunWorkerAsync();
// The stuff that is being executed in the backgroundworker.
loadImage.DoWork += (o, args) =>
    {
        // Loop through the list of items to find the matching picture.
        foreach (var item in listItems)
        {
            if (item.Name == name)
            {
                try
                {
                    // Get the image.
                    var request = WebRequest.Create(item.Picture);
                    using (var response = request.GetResponse())
                    using (var stream = response.GetResponseStream())
                    {
                        Image image = Image.FromStream(stream);
                        args.Result = image;
                        return;
                    }
                }
                catch (Exception)
                {
                }
            }
        }
    };
// Execute this when the backgroundworker is finished.
loadImage.RunWorkerCompleted += (o, args) =>
    {
        pictureBox1.Image = (Image)args.Result;
        Application.DoEvents();
    };

我做错了什么吗?如果有，你能告诉我是什么吗?