digging the litter almost completely out of the LK then just sitting on top

[zenman]

I have 2 cats that are bro (Leo) and sis (Simba) from same litter and are 7 months old. Both have shared a large covered pan in the bathroom right next to the toilet since they were litter trained with no problems at all. Simba is a digger. I have tried different depths of litter and no matter what she is digging to the bottom to the point that there are scratches in the bottom of the pan and she looks like she was in a dust storm. I just purchased the LK and placed it in place of the normal pan and put away the old one like instructed. Leo seems to have no problem, but Simba was just digging the litter almost completely out of the LK then just sitting on top of the LK all dusty. She does not go, she just sits there. I tried more litter / less litter, same thing. I sat there with her trying to encourage her until she got to the point of letting me know she had to go but wouldn't use the LK. I reset up the old box and away she went like normal (Also the digging to china part.) HELP !