[ferret_users] stippled figure cannot Fprint to PS

[Kelin Zhuang <kzhuang@xxxxxxxxxxxxxxxxx>]

Dear Ansley and all,
I stipple a figure but I couldn't Fprint it to PS or PDF and shows the 
error as:
GKSM item 12130950 is undefined
ggetgksm()  163 Metafile item is invalid
greadgksm()  162 No item is left in GKS Metafile input

set mode meta Fig.plt
use ens
use sig
shade mean[d=1]
plot/over/nolab/vs/symbol=dot/color=black a,b
cancel mode meta

Fprint -o Fig.ps Fig.plt
then I got the error.

Best regards,
Kelin