Parser Error Message: 'sistetma.tickets' is not allowed here because it does not extend class 'System.Web.UI.Page'.

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="tickets.aspx.cs" Inherits="sistetma.tickets" %>

using System;
 
namespace sistema
{
    public partial class tickets : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
...
        }
    }
}