Just completed a quick search, and some interesting information as appeared. Apparently a number of people are having problems with the ink cartridges for the Lexmark P915. Those using the black 32 have been adviced to use the 34 cartridge, and those using the colour 33 have been adviced to use the 35 cartridge. It would also seem that the Lexmark P915 as a clone via the Dell branding, and a modified carrier which needs a modified cartridge [lug moulded to cartridge cover].It would also seem, that if you remove the cartridge from the carrier then re-install, false error messages will appear, and the printer could malfunction.
These people may have the answer in their database click here