Hi there! I know this might sound strange, but are the things that Oliver is peeing on black (or dark coloured)? My Penny is 99.9% potty trained, but we have found that she couldn't resist peeing on anything black! We had a black mat, which we have now removed and just recently we put down a black blanket (not having made the connection to black) on our dogs' day bed - and she peed on that - any other colour doesn't have the same effect. Now that we have removed these items, she is 100% - I know!!! I said it might sound strange !!!