gdal - Why do I get different results with gdal_calc within the osgeo4w shell and QGIS' raster calculator?

I'm just wanting to make a simple map algebra operation in the osgeo4w shell using gdal_calc but I get wrong results when I divide one raster with the other. When I use the same rasters in QGIS and perform the same map algebra operation with raster calculator, I get no problem.