Indeed - it appears that your sample player is either not properly interpreting the Soundfont, or you haven't configured something properly. If the Soundfont is presented as a folder hierachy, though, have you tried clicking on the top level folder, and then playing it? If that works, see if you can detect the tone changing as you vary the playing strength. (the volume should of course change, but aside from that, there should be a tonal change as well).
I know absolutely nothing about those two pieces of software - sorry.
A free Soundfont player (as a VST plugin - not a standalone program) that I am pretty confident in working properly is SFZ
The fact that the various layers sound similar does give me confidence that it's a single instrument with different velocity zones though. If the Soundfont uses filtering to blend the layers, you may not notice any abrupt change in tone, though. (once you are able to play it properly)