Add a music album in itunes to nas

I would like to add new albums I download to my itunes library to a nas. I used to be able to do so on my macbook pro by dragging the album from itunes to the shared music folder on my nas. I find the nas on finder on my imac, and navigate to the nas shared music folder. However, I now cannot drag the album over to the shared music file and have it load on the nas. I do not want to move the entire itunes folder - just a few albums. Any help someone can provide would be appreciated.