无法拖放到PictureBox

Question

我在Winforms应用程序中拖放到Picturebox时遇到问题。当我尝试拖放图片时，我得到的图标看起来像this。它似乎没有采用我正在应用于图片框的AllowDrop。所有方法都在设计器中初始化。

这是我表格中的代码：

   private void Overlay_Load(object sender, EventArgs e)
    {
        pbx_OverlayImage.AllowDrop = true;
    }

    private void pbx_OverlayImage_DragDrop(object sender, DragEventArgs e)
    {
        MessageBox.Show("YAY");
        pbx_OverlayImage.Image = (Bitmap)e.Data.GetData(DataFormats.Bitmap, true);
    }

    private void pbx_OverlayImage_DragEnter(object sender, DragEventArgs e)
    {
        // See if this is a copy and the data includes an image.
        if (e.Data.GetDataPresent(DataFormats.Bitmap) &&
            (e.AllowedEffect & DragDropEffects.Copy) != 0)
        {
            // Allow this.
            e.Effect = DragDropEffects.Copy;
        }
        else
        {
            // Don't allow any other drop.
            e.Effect = DragDropEffects.None;
        }
    }

    private void pbx_OverlayImage_MouseDown(object sender, MouseEventArgs e)
    {
        var img = pbx_OverlayImage.Image;
        if (img == null) return;
        if (DoDragDrop(img, DragDropEffects.Move) == DragDropEffects.Move)
        {
            pbx_OverlayImage.Image = null;
            return;
        }
        pbx_OverlayImage.DoDragDrop(pbx_OverlayImage.Image,
        DragDropEffects.Copy);
    }

这是我用来调用表单的代码：

        var form = new Overlay {lbl_Title = {Text = txbx_OverlayName.Text}, pbx_OverlayImage = {AllowDrop = true}};
        //var form = new test();
        form.Show();

非常感谢你的时间。