Downloaded data from the site below. I unzipped them and tried to display in QGIS 2.14. It shows only black and white with min=0 and max=0.

http://sedac.ciesin.columbia.edu/data/set/gpw-v4-population-density-adjusted-to-2015-unwpp-country-totals/data-download

I must be doing something incorrectly.

Thanks,