I had the same problem with Misty, however, she much preferred the taste of the litter itself!

We hadn't gotten Bailey yet, but we were preparing and I got the litter box and put it in our ensuite where it would be and filled it with litter. We got the "World's Best Cat Litter" and she just loves that cornmeal taste!

We gave up and finally put the litter box in the ensuite shower stall (we never use it), duct taped over the drain, and fashioned a wooden block attached to the door to hold it open just enough for Bailey to get in, and bungy corded the door closed on the block.

Works like a charm!