In the .cmd file, change dopusrt.exe to the full path (usually "C:\Program Files\GPSoftware\Directory Opus\dopusrt.exe" including the quotes).
I would remove the "start" from the line as well, as the start command does silly things with quoted arguments and, since it isn't needed, the easiest thing to do is remove "start" and run dopusrt.exe directly.
(I also changed /cmd to /acmd so it works on the active window and not the source window, although they are usually the same.)
[code]@echo off
set inc=%1
set cnt=0
set num=1
for /d %%? in () do set/a num+=1
set rng=%num%
for %%? in (.*) do ( set/a cnt+=1&call :compare )
"C:\Program Files\GPSoftware\Directory Opus\dopusrt.exe" /acmd select range %rng%
goto :eof
:range
set/a num+=%inc%
set rng=%rng%,%num%
set cnt=0
:compare
if %cnt% equ %inc% call :range[/code]