For the Nautilus software to recognize a TWAIN compatible paper scanner, the drivers of the scanner must be installed prior to any scan attempt into the DICOM application. Once the drivers are installed and if necessary a computer reboot, open the Nautilus software with admin rights and go to configurations. You will find configuration settings under the tab "Scanner"
For installation of your scanner's drivers, please refer to it's user manual and installation CD.
You can also find popular brand name drivers online here: