The Unarchiver simply not working

I downloaded the app from the AppStore. For some reason it just doesn't work. Every time I want to extract a file it goes to the preference panel and I can't select anything and it won't extract anything. The message says : Setting The unarchiver as the default app. (I followed the steps, every Zip, RAR and other compressed files are set to open with The unarchiver as DEFAULT) Still getting that same preference pop up and no files are extracting. I have the latest iOS Macbook Pro late 2011. I don't want other app as replacement, I love the unarchiver. I used to be able to use it before but it stopped working for unknown reason. I want to know why it doesn't extract.