Before trying to perform OCR with Acrobat on PDF documents generated by BatchScanPlus (BSP) you should use Acrobat to print the document as another PDF file. That is right, you can generate a second PDF from the first one, from Acrobat, by printing it. Just select the proper page size and print the document from Acrobat. This step is mandatory if you want to perform OCR with Acrobat, to ensure compatibility between the PDF document and Acrobat OCR engine.
Also, if you will apply Acrobat OCR on the PDF file and you want BSP to insert numeration in headers or footers, always select Draw as Bitmap (in the Headers/Footers tab, inside BSP PDF creation window) to ensure compatibility with Acrobat.