#Caché

Until now i used $ZF(-1), in older Caché versión, now I try to use $ZF(-100), i do:

REST>w $ZV
Cache for Windows (x86-64) 2018.1.4 (Build 505_1) Thu May 28 2020 10:12:49 EDT
REST>s a=$zf(-100,"/SHELL","dir")
 
S a=$ZF(-100,"/SHELL","dir")
^
<NOTOPEN>

What is wrong?

Thanks in advance