How auto update pageload using Sqldependency

See more:

C#

ASP.NET

forms

I am trying to run a sqldependency method from a web form. I created "UpdateMethod", from a window-form.
However the web-form version, does not update the page-load automatically on the client-side, when there is a change in the database, whereas window-form does.

Window form method version:

delegate void GridDelegate(DataTable table);      
private void UpdateGrid()
        {
            string sql = "SELECT * FROM [dbo].[User]";
            DataTable dt = new DataTable();
            using (SqlConnection con = new SqlConnection(connectionstring))
            {
                using (SqlCommand cmd = new SqlCommand(sql, con))
                {
                    con.Open();
                    dep = new SqlDependency(cmd); //Passing Command to SQL dependency 
                    dep.OnChange += dep_OnChange;
                    using (SqlDataReader rdr = cmd.ExecuteReader())
                    {
                        dt.Load(rdr);
                    }
                }
            }
            dataGridView1.Invoke((GridDelegate)delegate(DataTable table)
            { dataGridView1.DataSource = table; }, dt);
        }

/////// web form ////////////
Web-form method version:

private void UpdateGrid()
        {
            string sql = "SELECT * FROM [dbo].[User] order by uploadDate desc";
            DataTable dt = new DataTable();
            using (SqlConnection con = new SqlConnection(GetConnectionString()))
            {
                
                try 
                {
                    using (SqlCommand cmd = new SqlCommand(sql, con))
                    {
                        con.Open();
                        SqlDependency dep;
                        dep = new SqlDependency(cmd); //Passing Command to SQL dependency 
                        dep.OnChange += dep_OnChange;

                        using (SqlDataReader rdr = cmd.ExecuteReader())
                        {
                            dt.Load(rdr);
                            // GridView1.DataSource = rdr;
                        }

                    }

                }

                catch (Exception ex)
                {
                    throw ex;
                }
            }
            GridView1.DataSource = dt;
            GridView1.DataBind();
        }

Am I missing something from my web-form method. Please advice. Many thanks.