problem att kolla status

Har följande:

{
public Ticket ticket;

    [SoapHeader("ticket", Direction = SoapHeaderDirection.In)]
    public void Comment(String name, String text, String email, String ip, int postid)
    {
        try
        {
            IsOnline(ticket.sTicket);

            newComent nc = new newComent(postid, name, text, email, ip);
            newComent.createComent(nc);
        }
        catch (Exception ex)
        {
            throw new Exception(ex.Message);
        }
    }

    private CreateNewTicket IsOnline(string ticket)
    {
        CreateNewTicket cnt = (CreateNewTicket)Application[ticket];

        if (ticket != null)
        {
            return cnt;
        }
        else
        {
            throw new SecurityException("Du är troligen inte inloggad");
        }
    }
}

public class CreateNewTicket
{
    #region Egenskaper
    private string username;
    public string UserName
    {
        get { return username; }
    }

    private string ticket;
    public string Ticket
    {
        get { return ticket; }
    }

    #endregion

    public CreateNewTicket(string uname)
    {
        username = uname;
        ticket = Guid.NewGuid().ToString();
    }
}

public class Ticket : SoapHeader
{
    public string sTicket;

    public Ticket(string ticket)
    {
        sTicket = ticket;
    }

    public Ticket()
    {
    }
}

Men när jag kör Comment får jag felmeddelandet:
Object reference not set to an instance of an object.
på raden: IsOnline(ticket.sTicket);

Hur löser jag detta??

Tacksam för all hjälp :stud

public Ticket ticket=new Ticket();

...kanske?

ok, löste det med Session :bire