Forgive me for the lenghy post but I wish to provide as much detail as possible. Our two cats have been using Litter Robot for 7 weeks now with no problem. Last week I found poo, twice, on the mat and step (waste drawer). It looked like one of them defecate as they enter Litter Robot. We finally caught Fred in the act- it's not like he can't hold or anything; he defecate right after he enters so some was on the mat, some on the step, & some in the litter. He also urinates right by the entrance. While his sister Ginger also does the same thing, we haven't caught her defecate like her brother. Both of them used to enter litterbox, do some digging, turn around facing outside and do their business. Now they simply go in & do their business right by the entrance. We took them to the vet first week in June, besides mild gingivitis both are healthy. Their diet consist of 1/2 cup of Nutro dry in the morning, 3 oz canned (split between the two) in the evening. We started offering canned food last week. Because both received a clean bill of health from vet we think it's a behavior problem, or maybe it's more calming facing inside . Starting last week I mixed some baking soda in the litter. I suspect perhaps they do not like it in the litter so yesterday I cleaned the globe & drawer, refilled with fresh litter (we use World's Best). So far Fred hasn't use it to poop but I'm keeping my fingers crossed. Does anyone have any input as to why they change the way they use litterbox? I will switch to a bigger litter box if necessary but I want to try change other things first. The litter is expensive and it's been more than 60 days so we can't get a refund.