[Mono-list] A null value was found

[e26659@uajms.edu.bo]

Hello:

I'm working with xsp server of MONO::

But When I'm start my application in page "aspx" the server reporting this
problem:
--------------------------------------------------------------------
Error Message:

Stack Trace:

System.NullReferenceException: A null value was found where an object
instance was required
in <0x0006f> 00 ASP.inicio_aspx:entrada (object,System.EventArgs)
in <0x0005a> 01 System.MulticastDelegate:invoke_void_object_EventArgs
(object,System.EventArgs)
in <0x000a6> 00 System.Web.UI.WebControls.Button:OnClick (System.EventArgs)
in <0x0005b> 00
System.Web.UI.WebControls.Button:System.Web.UI.IPostBackEventHandler.RaisePostBackEvent
(string)
in <0x00016> 00 System.Web.UI.Page:RaisePostBackEvent
(System.Web.UI.IPostBackEventHandler,string)
in <0x00048> 00 System.Web.UI.Page:RaisePostBackEvents ()
in <0x0011b> 00 System.Web.UI.Page:ProcessRequest (System.Web.HttpContext)
in <0x001b0> 00 .ExecuteHandlerState:Execute ()
in <0x0004e> 00 .StateMachine:ExecuteState (IStateHandler,bool&)

--------------------------------------------------------------------

I think that this problems happend when three or must client access at the
page .

I was testing this problem:
 1. - I think that this problem happend when
  ex:
       String dato = (string) Session["date_ant"] // the problem don't happen
       Response.Write(dato);
       // The problem with session happend
          Because the value of "dato" lossed


Remember that "Session" in Mono 0.23 don't  work

But
In the Mono 0.24 work but the problem happend "A null value was found
where an object instance was required"

Now in MONO 0.25 the problem continue
----------------------------------------------------
Miguel Icaza We suggest the line :
       Console.Write("valor devuelto=", GetType());

This order response with
valor devuelto ASP.Session_aspx

I NEED YOUR HELP
thanks for your attention