There are various reasons related to it so start playing Happy Mall Story by following the below-listed solutions only:
Check your internet connection first because sometimes things can go wrong due to poor connectivity issues. So, try to use any other Wi-Fi network or mobile data if possible and then play Happy Mall Story again.  It will definitely work fine now without any problem at all!
You might be playing hasty which is not good for winning any level at all. Therefore, make sure to play Happy Mall Story game patiently and with full concentration otherwise, you will end up losing the game.