my epson DX3800 is telling me the ink cartridges are empty but they are brand new. Can anyone advise ?
If you bought unofficial printer cartridges (eg cheapo ones not made by Epson), then sometimes this can happen. It's becuase they have a chip in the cartridges that tell the computer how full they are, and on cheapo ones, dodgy chips don't work very well. On my epson I just keep printing until the colours start to go funny (they've run out).
Yep, sometimes Epson cartridges have chips, so you'll need to buy the appropriate chipped cartridges.