i suggest you to use "reclassify grid values" SAGA module in processing it's more intuitive than raster calculator s. -- View this message in context: http://osgeo-org.1560.x6.nabble.com/unable-to-produce-a-raster-mask-tp5174314p5174466.html Sent from the Quantum GIS - User mailing list archive at Nabble.com.