The toner cartridge for the color indicated on the second line of LCD is not installed correctly.
Pull out the drum unit. Take out the toner cartridge for the color indicated on the second line of LCD, and then put it back into the drum unit following the steps below:


NOTE: Illustrations shown below are from a representative product and may differ from your Brother machine.

1. Make sure that the machine is turned on.
   
   
2. Press the front cover release button and then open the front cover.
   
   
   
   
   
   
3. Hold the green handle of the drum unit. Pull the drum unit out until it stops.
   
   
   
   
   
   
   
4. Hold the handle of the toner cartridge and slightly push it toward the machine to unlock it. Then pull it out of the drum unit.
   
   
   
   
   
   
   
   

   • DO NOT put a toner cartridge into a fire. It could explode, resulting in injuries.
     
     
   • DO NOT use cleaning materials that contain ammonia, alcohol, any type of spray or any type of flammable substance to clean the inside or outside of the machine. Doing this may cause a fire or electrical shock.
     
     
   • Be careful not to inhale toner.
   
   
   
   
   
   
   
   

   • We recommend that you place the drum unit and/or the toner cartridge on a clean, flat, level, stable surface with a sheet of disposable paper or cloth underneath it in case you accidentally spill or scatter toner
     
     
   • Handle the toner cartridge carefully. If toner scatters on your hands or clothes, wipe or wash it off with cold water at once.
     
     
   • To avoid print quality problems, DO NOT touch the shaded parts shown in the illustration.
   
   
   
   
   
   
   
5. Hold the handle of the toner cartridge and slide the toner cartridge back into the drum unit, then slightly pull it toward you until you hear it click into place. Make sure that you match the toner cartridge color to the same color label on the drum unit. 
   
   

C-Cyan M-Magenta Y-Yellow K-Black

6. Push the drum unit in until it stops.
   
   
   
   
   
   
7. Close the front cover of the machine.

If the problem continues, call your dealer or Brother customer Service.