Printer Repair Questions? Ask IT Technicians for Answers ASAP
Are you using genuine Xerox replacement toners?
If not, then the machine may not recognize it.
If you are using Xerox replacement toners, then check that the small sensor inside the machine is clean - you can use compressed air to help blow off any debris or dust that may have built up on it.
If that doesn't help, try fitting another new toner cartridge.