Using Automator to Add Metadata from Folder Structure

I have a huge set of .wav files organized in a folder structure like this:

Artist->Album->Song

I am trying to write an Automator workflow to import each song into iTunes whilst adding Artist and Album metadata. I can get the workflow to work for a single artist with a single nested album, but multiple nested albums result in Artist and Album tags which are concatenated versions of all the artist and album names. This is my workflow:

I'm using variables to store the artist name and album name. Somehow, when this gets to "Set Info of iTunes Songs", the artist and album info gets concatenated. Any ideas much appreciated. Thank you.