stuck on level 71

I just bought this game and was enjoying it until level 71. I can not break one of the squares. I have tried everything and played it many times over and over again. I sure would love to be able to finish the game so if anyone knows how to get past this point please let me know

Hi,
I clear the rest of the board first. Then I concentrate on that one spot until I get a snowball to drop into that slot. It sounds harder than it is, but it has worked every time.