GDI+ DrawLine between two imagebuttons on webpage

Question

I have couple of imagebuttons on the webpage
User clicks on any two of them , i pass the coordinates of those selected imagebuttons to DrawLine()
It draws a line but the entire webpage becomes blank,only the line at the top left corner appears
Please help, its urgent, I wilbe be very happy if anybody can let me know with example what is going wrong
Email : [email protected]
i have uploaded the code that i am using for reference
Thanks in advance

 private void drawLine(int x1, int y1, int x2, int y2)
        {

                Point point1 = new Point(x1, y1);
                Point point2 = new Point(x2, y2);
                Bitmap objBitmap;
                Graphics objGraphics;
                objBitmap = new Bitmap(200, 200);
                objGraphics = Graphics.FromImage(objBitmap);
                objGraphics.Clear(Color.White);
                Pen p = new Pen(Color.Black,1);
                Rectangle rect = new Rectangle(10, 10, 280, 280);
                objGraphics.DrawLine(p, point1, point2);
               
                objBitmap.Save(Response.OutputStream, ImageFormat.Gif);
               objBitmap.Save(Server.MapPath("/images/x.Gif"), ImageFormat.Gif);
                objBitmap.Dispose();
                objGraphics.Dispose();
          }
}