Difficulty with a unified skin

#1

I just finished making a rough Zsketch for a quadruped, and want to make a unified skin. However, when I attempt to create it, a lot of the anatomy is incorrect or lost, particularly around the tails and ears (which are very large). Parts of the legs and feet also seem to be missing.

The Zsketch:

The unified skin:

I’ve tried varying the settings quite a lot, with the above link showing my best result. I’m aware of the option of using an adaptive skin, but I’d really like to know why I’m having this issue, and how to avoid it in the future. Does anyone happen to have a potential solution?

(Zbrush 4R6, Windows 7 64-bit, around 18,000 active points on the Zsketch)

#2

I’ve managed a partial solution by using Unify in the Deformation subpalette. It shrunk the Zsketch down to a dot, and trying the Unified Skin on it in this state produced this:

It has some jags around the edges of the tails and ears, but it’s quite close to satisfactory. I used the manual deformation tools to scale it back up again afterwards. Can I improve it any further?