So when Rooter is behind the crates - get him on the floor.
Click the "Rooter Nose" icon that he has available - and click on the thing blocking Ace from getting over there.
Warning - All in one word.
YoUwiLlWaNtToConTroLAcEbEfoReDoInGsOaNdMoVeHiMoUtOfThEwaYofBeInGrUnOvER
Strike through to make it difficult to read so you don't accidentally get spoiled. :) Might be fun to try it and see what happens.