Expert chests

I've spent 110 coins just to get a book chest yet I didn't get it in 3 days ago. Ever since that I don't see a single book chest (3 days in a roll)

Friend asked me why not spend coins to get extra challenges to hunt for book?
My answer is : if 3 days in a roll doesn't even a single book show what makes u feel I will get a book when I spend another 2 coins?

I'm really getting more n more disappointed bout this game

I got a Adv physical chest from Jungle exp 5 tonight after 4 challenges in other maps without seeing a chest. I also have received 4 intermediate chests from Team FC today. They arent advance but better than nothing I guess. Oh the skill I got from adv chest was Kamikaze.