Instruct: Classify Amazon reviews into positive or negative sentiment
Query: One important feature is missing for this litter box

I made one stupid mistake again on buying things without reading reviews here, which is buying this litter box. I installed the box and poured in the litter. Hours later I returned to found a piece of cat poo on the floor. I assume that the height of the bowl is so low that when the cat tried to dig the litter to cover the poo and one piece got knock out. So I bought some plastic mat and circle the bowl with the mat, leaving an opening where the conveyer is. Now no more poo knocked from the bowl, but some litter sand still flies over from the conveyer opening. If you don't mind vacuuming everyday around the bowl, I guess it is ok. I think one simple modification can get this box to a 5 star item. The manufacturer can easily design a top part of the unit with a door, so that the cat can get into the bowl and no litter gets spilled out. I just wonder who was use testing this item, or if it got use test before they made it.