geoserver - Chaining Rendering Transformations: Making isotherms using Barnes Surface + Contour process?

I'm trying to calculate isotherms following the istructions showed in the post on OSGeo blog (http://blog.opengeo.org/2013/01/10/chaining-rendering-transformations-in-geoserver/)

I'm using GeoServer 2.2.3 on a Windows 7 machine (8 Gbyte RAM, biprocessor)

I've a shapefile with points and temperature and I'm trying to use the Meteo-1.sld

Using the layer in preview

http://:8080/geoserver/CesareWorkspace/wms?service=WMS&version=1.1.0&request=GetMap&layers=CesareWorkspace:CentralineTemperature-01-01-2001&styles=&bbox=318287.0,4880823.0,515945.0,5142603.0&width=386&height=512&srs=EPSG:32632&format=application/openlayers

it works fine but when I try to use le Meteo-1.sld

http://:8080/geoserver/CesareWorkspace/wms?service=WMS&version=1.1.0&request=GetMap&layers=CesareWorkspace:CentralineTemperature-01-01-2001&styles=&bbox=318287.0,4880823.0,515945.0,5142603.0&width=386&height=512&srs=EPSG:32632&format=application/openlayers&STYLES=Meteo-1

the map is white. It seems that there are no errors in the log.

When I try to use the Barnes Surface WPS directy (gs.BarnesSurface), I obtain a black tiff ....

At the following link https://www.dropbox.com/sh/fmbdhzwp5mobpcq/lf43d3SykM there are:

• data.zip --> the shapefile I'm using


• Meteo-1.sld --> the sld I'm using


• geoserver.log --> geoserver log

Could someone tell me which configurations I've to use in the sld for my data? Or give me a sample data and a sld that works?