Problem With Network.download On Android

Hi guys, I have the following piece of code to call a web service:

[lua]function UtilWebService:call§
   if string.len(cfgParams.urlServidor) == 0 then
      native.showAlert(app.name, “No se ha configurado la URL del servidor”, {“Aceptar”})
      return
   end

   – Listener de la llamada
   local function networkListener(event)
      local res

      if event.isError then
         native.showAlert(app.name, “Error de conexión con el servicio web”, {“Aceptar”})
      else
         res = json.decode(event.response)
        …
      end
   end

   – Parametros que se le van a pasar a la URL
   local params = {}

   network.request(cfgParams.urlServidor, “POST”, networkListener, params)
end
[/lua]

When I call network.request with a correct url (cfgParams.urlservidor), everything works perfectly, but when I call request network with a erroneous url, instead of giving the error message “Error de conexión con el servicio web” get the following error:

[lua]H:\GpBusiness\Fersoft\UtilWebService.lua:70: java.lang.NullPointerException
Java Stack Trace:

network.NetworkRequest$AsyncNetworkRequestRunnable.(NetworkRequest.java:1133)

network.NetworkRequest.invoke(NetworkRequest.java:1859)

com.ansca.corona.JavaToNativeShim.nativeMultitouchEventCallback(Native Method)

com.ansca.corona.JavaToNativeShim.multitouchEventCallback(JavaToNativeShim.java:280)

com.ansca.corona.events.MultitouchEvent.Send(MultitouchEvent.java:31)

com.ansca.corona.events.EventManager.sendEvents(EventManager.java:274)

com.ansca.corona.Controller.onDrawFrame(Controller.java:228)

com.ansca.corona.opengl.CoronaGLSurfaceView$CoronaRenderer.onDrawFrame(CoronaGLSurfaceView.java:379)

com.ansca.corona.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1622)

com.ansca.corona.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:1377)
stack traceback:

C: in function ‘request’

H:\GpBusiness\Fersoft\UtilWebService.lua:70: in function ‘call’

H:\GpBusiness\sincronizacion.lua:244: in function ‘sincronizarDatos’

H:\GpBusiness\menuprincipal.lua:93: in function ‘_onEvent’
?: in function
?: in function [/lua]

This error only appears if my application works on Android 4.0, since in Android 2.6, it works correctly, giving my error message when you put a wrong url.

I hope you can help

greetings and thanks in advance