GridView1_RowUpdating is not working. .

//for example see this 

//in gridview put this property 
// DataKeyNames="Id"


 protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {
        GridViewRow row = (GridViewRow)GridView1.Rows[e.RowIndex];
        int id = Int32.Parse(GridView1.DataKeys[e.RowIndex].Value.ToString());
        Label id = (TextBox)row.FindControl("Label4");
        TextBox city = (TextBox)row.FindControl("TextBox3");
        SqlCommand cmd = new SqlCommand("update query ", con);
        
//for example of update query
   
//update tablename set column=city.text where id=convert.toint16(id.text) ;  
 
        con.Open();
        cmd.ExecuteNonQuery();
        GridView1.EditIndex = -1;
        bind();
    }