This feature is intended for use by Samsung's own apps. When used in a third party app, it may not work.
If there comes a day when Samsung makes this official and supported, I'll treat such cases as a bug.
Until then --
If it doesn't work on a particular Samsung device / firmware flavor, well, just pretend it wasn't there in the first place.
Or switch to Nova, Apex, or Smart Launcher, where this is an officially supported feature.
Or use Aqua's message counter widget.