Hello Warfina,
KittyCatS sleep for 8 hours and are awake for 8 hours. When they sleep and their energy is below 25%, they won't wake up, but if they are asleep and energy is 25-99%, you can wake them.
You say it has lasted four days - could it be that you have been unlucky and have been online and tried during those 2 hours of the cycle where he is asleep, but not yet over 25% energy?
Oh, and if your cat is a kitten (below 7 days), the sleeping cycle is different - only 4 hours asleep and awake instead of 8.
Best of luck with it
-Saga