private void btnName_Click(object sender, EventArgs e)
 {
     agent_list = admin.Searched_Agents_with_Name(txtName.Text);
     if (agent_list.Count() != 0)
     {
         gridAll.DataSource = agent_list;
     }
     else
     {
         MessageBox.Show("There is no result for given condition.", "NO RESULT");
     }
 }