look in the tightest, darkest spot, closest to the place of escape. If you don't think he can be some where, that is where he is.

I once had a cooler on the dining room table. I put the ball python in the cooler while cleaning out the tank. I got side tracked, and came back an hour later. To my horror the ball was gone.

Well to make a long story short, I searched the entire room... from top to bottom. did this for about 4 hours. at the end I was litterally crying like a baby (I am 32 years old). Then, my wife found him. No more then 3 inches from the cooler. he had climbed inside of the paper towl roll sitting on the table! I still to this day have no idea how he could have possibly gotten his big butt in there. but, he did it. he was totally concealed in the roll. the only way my wife found it was that the paper towls weighed way more then they should have. I actually had to cut the roll to get him out!

Point is, look EVERYWERE imaginable within about 10 feet of where it escaped.