Fehler in der Anwendung!

Beschreibung:
System.NullReferenceException: Object reference not set to an instance of an object.
   at INPLAN.clsSession.SetDefaultLanguage()
   at InplanWeb.Start.Page_Load(Object sender, EventArgs e)
   at System.EventHandler.Invoke(Object sender, EventArgs e)
   at System.Web.UI.Control.OnLoad(EventArgs e)
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)