Hello!
I DID SEE *THIS* on the HPLIP website
http://www.hplipopensource.com/hplip-web/index.html
under the DeskJet 2540 AIO:
You have selected Ubuntu 12.04 using the HP Deskjet 2540 All-in-one Printer.
Ubuntu 12.04 supplies HPLIP 3.12.2 by default, which does not support your printer.
You must ensure latest HPLIP version (recommemded), or at least HPLIP 3.13.8 in order to use your printer with Ubuntu 12.04.
If you downloaded and installed HPLIP 3.14.4 (the current version), you can:
1. Start by removing and reinstalling the printer within HPLIP.
2. Per the instructions on the HPLIP website, remove the current HPLIP install, download HPLIP again, and reinstall it. If HPLIP is installed following their instructions to the letter, you shouldn't experience any problems.
There are so many things that can go wrong when installing HPLIP that unless someone walks you through it by phone or TeamViewer, it is virtually impossible to determine exactly where your install might have gone wrong.
Further support for HPLIP can be obtained by filing a trouble ticket here:
http://hplipopensource.com/hplip-web/support.html
As Linux users, we are BLESSED that HP cares enough about us to have made the effort to develop and maintain HPLIP. For virtually every other printer out there, Linux driver development support is either an afterthought, or it has been left up to the user community to develop their own solutions.
If HP only supported my LaserJet 3100 AIO. NOT happenin'; it's an 'orphan' printer... :'(
73 DE N4RPS
Rob