...

Edit:

I've found a reason in the meantime:

if App_Scriptpath is located on "C:\" and App_Scriptpath HAS NO SUBFOLDERS inside, DIR_Exists("C:\") returns wrong result !

Save this file to some empty folder ON YOUR "C:"-Drive and run it.
Thereafter create a new subfolder - inside that previously empty folder and next to this script - and run again.