Ho una pagina così composta:

Default3.aspx
codice:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="Default3" %>


<!DOCTYPE html>


<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    
        Arrival date:<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <asp:RangeValidator ID="RangeValidator1" runat="server" ControlToValidate="TextBox1" ErrorMessage="RangeValidator" Type="Date">Intervallo non corretto!</asp:RangeValidator>
        <br />
        <br />
        <asp:Calendar ID="Calendar1" runat="server" OnSelectionChanged="Calendar1_SelectionChanged"></asp:Calendar>
        <br />
        <asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />
        <br />
        <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
    </div>
    </form>
</body>
</html>
Default3.aspx.cs
codice:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;


public partial class Default3 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        RangeValidator1.MinimumValue = DateTime.Now.ToShortDateString();
        RangeValidator1.MaximumValue = DateTime.Now.AddDays(14).ToShortDateString();
    }


    protected void Calendar1_SelectionChanged(object sender, EventArgs e)
    {
        TextBox1.Text = Calendar1.SelectedDate.ToShortDateString();
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        if (Page.IsValid)
        {
            Label1.Text = "Il tuo arrivo è previsto per: " + TextBox1.Text.ToString();
        }
        
    }
}
La validazione non funziona! Il sistema dovrebbe avvisare se la data scelta dal calendario supera di 14 giorni quella attuale, ma niente, non va! Cosa sbaglio?