Tooltip on Calendar at Dayrender event

Question

I want tooltip display on calendar selected date as stored in database on day render event.I Have written the code but it diidnt work

System.Web.UI.WebControls.Image image;
               image = new System.Web.UI.WebControls.Image();
               image.ToolTip = row["Event_type"].ToString();
               e.Cell.Controls.Add(image);
               e.Cell.BackColor = Color.Wheat;