Aaaaaaaaaah!
"With SMT Button pressed mesh will be Smoothed then Divided"
Forgot this damned button (that arrive with this Boeing's Interface :)
All is fine! :)
So export from moi to Zbrush is cool in OBJ format for some crazzy sculptures

PS So my trick was useful but unnecessary :)

"With SMT Button pressed mesh will be Smoothed then Divided"