how to get hazel to wait while it opens a file

hi all,
i'm using hazel for a while and its great but now i need it to do a task that incorporate using another application.
basically i have a folder that contains more folders in it, and in each folder there are rar file. i need to extract all those rar files and then move the extracted file to another folder.
it looks something like this

A
--a1
-----file1.rar
--a2
-----file1.rar
--.
--.
--.
--a50
----file1.rar

i have made a rule for the hazel to go into each sub folder search for a file extension that is rar and open it, however because it uses another application to extract the file ( i use rucksack) it doesn't wait for the files finish extracting before it tries to extract the other files, and what i'm ending up with is that hazel is trying to extract all the 50 files almost simultaneously, and for some reason rucksack just ignores all the files except the first so i end up with just one file being extracted.

if you know of a way to make hazel wait till the file is extracted before continuing to next file it would help me a lot

thanks

Perhaps you could just start using The Unarchiver instead of Rucksack. It will queue up jobs.