Gridview tooltip

Question

Hi All,

 if (e.Row.RowType == DataControlRowType.Header)
        {
            int i = 0;
            foreach (TableCell cell in e.Row.Cells)
            {
                cell.Attributes.Add("title", reason[i]);
                i++;
            }
        }

i am using this code to show tool tip in grid view.Tool tip is getting displayed when the page loads but after a click event the tool tip is not working.