Is your user in the scanner group?
Edit:
sudo gpasswd -a YourUsername scanner
Edit the file /etc/sane.d/dll.conf and uncomment the line:
#hpaio
Edit: If hpaio is not in the file you have to add it.
Test the scanner with
hp-scan
Is your user in the scanner group?
Edit:
sudo gpasswd -a YourUsername scanner
Edit the file /etc/sane.d/dll.conf and uncomment the line:
#hpaio
Edit: If hpaio is not in the file you have to add it.
Test the scanner with
hp-scan