The Wonderland Board

Okay I'm dense. I've played and played and can't figure out what I'm doing wrong. I get 2 kabooms down and they blow up some of the boxes. Then I trap the 3rd kaboom and he blows up more boxes. I get the 2 keys from the houses. But there is one box left in front of the path down at the bottom. If I slide it down and through the wall I just keep bouncing back. But since it's blocking the path I have to slide it. What am I doing wrong????

Did you look at the online solution? It gives detailed instructions on how to complete the entire level. Good luck!