Make sure you have the recommended number of Breeze Litter Box Systems, (one system per cat, plus one extra). Some helpful tips also include:Check the tray for pee. If pee is present in the tray: Remove the OLD box, as this will allow the cat plenty of time to become acclimated to the new pellets. If urine is not present,  follow the steps below: Empty and clean the OLD box(es) with a mild soap and start with fresh litter. Keep the Breeze Litter Box System next to the OLD box. Combine the existing litter in the OLD box with 2 cups of Breeze pellets. Each day, maintain the OLD box and add ¼ cup of Breeze litter pellets until the OLD box contains 70% Breeze litter pellets and 30% old litter. If cat continues to use the OLD box with this 70/30 mixture, slowly start reducing the amount of litter in the OLD box by ½ cup per day until there is hardly any litter left in the OLD box. Once your cat is consistently using the Breeze Litter Box System to pee and poop, remove the OLD box.