If you still haven't gotten it to work, you may try pulling the cartridges out and wiping them very gently with a soft tissue. Sometimes ink gets on the little chip on the side and causes problems.
You say you've changed cartridges, so if they have all been changed, that wouldn't be it.
Try taking them out and see if you can access the underside of the carriage. Gently clean with q-tips.
Seems I had this problem with an old Epson and we ended up getting it clean...
BTW, fellow Epson lover here!! I've got an R220 that I've run through the wringer. About to replace it with the new Artisan 800 in a few weeks! I won't print photo or graphic print jobs on anything but an Epson!