rong | rong approach to wrong inputs | Validation library

public partial class _Default : Page
{
    List listOfCustomers = new List();
    protected void Page_Load(object sender, EventArgs e)
    {

        listOfCustomers.Add(new Customer { Id = 1, Name = "Adam", Surname = "Bong" });
        listOfCustomers.Add(new Customer { Id = 2, Name = "Bob", Surname = "Tong" });
        listOfCustomers.Add(new Customer { Id = 3, Name = "Colin", Surname = "Wong" });
        listOfCustomers.Add(new Customer { Id = 4, Name = "David", Surname = "Rong" });

        if (!Page.IsPostBack)
        {
            gridCustomers.DataSource = listOfCustomers;
            gridCustomers.DataBind();
        }
    }

    protected void gridCustomers_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            LinkButton lbMoveUp = (LinkButton)e.Row.FindControl("lbMoveUp");
            LinkButton lbMoveDown = (LinkButton)e.Row.FindControl("lbMoveDown");

            Customer c = (Customer)e.Row.DataItem;

            lbMoveUp.CommandArgument = c.Id.ToString();
            lbMoveUp.CommandName = "MoveUp";
            lbMoveDown.CommandArgument = c.Id.ToString();
            lbMoveDown.CommandName = "MoveDown";

            if (c.Id > 0)
            {
                if (e.Row.RowIndex == 0)
                {
                    lbMoveUp.Visible = false;
                }
                else if (e.Row.RowIndex >= 1 && e.Row.RowIndex < listOfCustomers.Count - 1)
                {
                    lbMoveUp.Visible = true;
                    lbMoveDown.Visible = true;
                }
                else if (e.Row.RowIndex == listOfCustomers.Count - 1)
                {
                    lbMoveDown.Visible = false;
                }
            }
            else
            {
                lbMoveUp.Visible = false;
                lbMoveDown.Visible = false;
            }
        }
    }
}
public class Customer
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Surname { get; set; }
}

NoReverseMatch at /valoare/MICA/ Reverse for 'contract_list' with arguments '()'
and keyword arguments '{'valoare': 'MICA', 'tip': 'BUNURI'}' not found.
1 pattern(s) tried: ['valoare/(?P[A-Z]{4})/(?P[A-Z]{8})/$']