Problem

[Karena]

Last week, one of my children accidentally shut the door to the room where Simba's litter tray is and because he couldn't get to it to do his poos he went in Maggie's bed (don't laugh). We forgave him for this because he had no option not being able to get to his litter tray. The problem is now he seems to prefer going there than his litter tray. He has been doing his wees in the litter tray but once a day when he does his poos he has been going in Maggie's bed. How do I stop this now? Please help!!!!!!!!!