The sensor that detects it can be dirty. You may have a defective bottle. Worst case scenario would be the drive gear in the back that engages the bottle may be broke. I would have it checked by a technician. You don't want to get a waste toner backup, its a big job to fix.
There are no steps, you just reseat pr replace it (Toner and waste toner are not the same things)
Open the door and look to the right of the trays