I've been using Poser since 7 & run into this issue on a few skin sets but never got it sorted.It seems to be the skins that do not have the brows painted directly on them.I've made the eybrow boddy part visible but still no joy.Specifically right now I'm working with Shaaelia’s otherwise great Forensic Investigator  http://www.sharecg.com/v/60143/gallery/11/Poser/Updated-Forensic-Investigator-Skin-for-V4   Am I just missing something obvious?

I have a similar problem in Daz, and i click on the parameters of head eyebrown not visible. i do not know if this can be useful

In the material room see what texture files the model are using then select face or eyebrows material and see if it has a file associated with. Perhaps you need to point to the right file.

Hope this helps. I use Poser 7 too. I've had some problems with textures that were usually the named materials not having a texture file assigned to it.