请教picturebox滚动条的问题

                tabControl1.TabPages.Add("Image");
                tabControl1.TabPages[5].AutoScroll = true;
                PictureBox wcfPic = new PictureBox();
                wcfPic.Image = Image.FromFile(DefaultPath + "\\" + ImageFileName);
                wcfPic.Parent = tabControl1.TabPages[5];
                wcfPic.Dock = DockStyle.Fill;