If you do not have at least DS4 installed on your system, you much make sure the install DS4.x files is checked when you install the DSON importer.

This gives the module the DS4 files it needss to "translate" it into Poser speak. 

If you have a version of DS4 installed, it doesn't matter.  Also make sure the DSON importer is installing to the Python folder inside the Runtime folder which is in the main Poser app folder.  This is where it looks for it by default.

Some users get decent results using DSOn and others get crappy results.  I've always ended up with crappy results so I won't say mucy more....