I checked the specs, and you can only get 1200 dpi from the glass and 600 off the feeder. Are you placing the original on the document glass?
yes of course.
I installed the drivers from the CD. In the Easy Documentum Creator there's no option for 1200 dpi (max. 600), I tried it with documentum glass and ADF too.
I tried it with Acrobat DC too, and there is an option for 1200 dpi, and 2400 dpi, but the scanning progress is failed (but 300 dpi works in Acrobat).
Unfortunately, I don't know why that is not working. I would recommend contacting Support to speak with a Product Specialist: 1-800-821-2797