i have a problem with namespace in the contact.aspx.cs

i have customised the contact code behide to something like this
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace MB.KenakoSystems.UI
{
    public partial class Default2 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }
    }
}
 
without the namespace the file is building without errors but when i introduce the namespace i get the following 4 errors
make sure that the class define in this code file matches the 'inherit' attribute and that it extends the correct base class(eg page or UserControl) 'ASP.contact_aspx.GetTypeHashCode()':no suitable me ...