Session in WebService with ASP.NET - Please Help

[Juan Irigoyen]

I have a page asp that call the webmethod, this make the variable of session
but when the webmethod return the values stored
in webmethod lost.

In the web.config have the next code

<sessionState mode="InProc" cookieless="false" timeout="20"></sessionState>

[WebMethod(EnableSession = true)]
public int GestionTicket Inicio()
{
Session.Add("SesionNivel", 1);
Session.Add("SesionTipo", "a");
Session.Add("SesionAccesos", 0);
return 1;
}