Unfortunately, Acrobat is a bit picky when it comes to scanners. I've noticed this over the years with different versions of Acrobat and different scanners. I would try to re-install the scanner software to see if that fixes the problem.
Even if you cannot make your scanner work with Acrobat, you can still use Acrobat's features to optimize your scanned document: Scan with the software that came with your scanner, either directly to PDF if there is such an option, or to TIFF images. Make sure that you select a reasonable scan resolution (e.g. 600dpi black&white or 300dpi grayscale or color). Once you have scanned your document, open Acrobat and import these scanned page. If you were able to scan directly to PDF, just open the PDF file. If you have a number of TIFF images, select File>Create>Combine... and select all your TIFF images in the correct order. Make sure that you click on the Options button and select "Large file size" and Single PDF.
Now that the document is in Acrobat, you can run Tools>Optimize PDF>Optimize Scanned Pages to apply the same processing steps that you could have applied when scanning directly into Acrobat.
Karl Heinz Kremer
PDF Acrobatics Without a Net
PDF Software Development, Training and More...
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