Tip 91 - About Epson new cartridges T073/73N etc
Since August 2008, Epson released a new range of printers and cartridges (like T073/73N cartridges) which will only work with each other.
CX9300F made before August 2008 can take T0731, 732, 733 and 734 cartridges, and T073/73N cartridges.
CX9300F made after August 2008 can only take T073/73N cartridges.
If you are unsure when your printer is manufactured, just check your user manual and see what cartridges do it need.