try again the 4.17pre20 or 21 and remember to replace not only the executable but even the Modules, dopus.library and the DopusRT.
PROGDIR:DirectoryOpus
PROGDIR:Modules/
ConfigOpus--Dopus_Disk--Dopus_Icon--Dopus_Print
SYS:C/DopusRT
SYS:Libs/dopus.library
Do an Avail Flush (or reboot) after the new installed components and remember that the catalogs of the 4.12 are NOT compatible with the latest versions.
If you still have problems, uncheck the "Use ExALL()" option, in the "Configuration>System>Directories" section.