This is super agrivating. I have a brand enw 15" mbp and i had my downloads and documents folders on the right they were in stacks and i accidentally pulled downloads off... POOF, thats gone. Couldnt get that back. Grabbed the documents and were able to move it around in the dock but once i pulled that off...poof. Tried to get any of them back. nope. Went into finder/ name of my mac and tried to drag either back into the dock.. FAIL. I know...to the right of the dotted line. still doesnt work. NO FOLDERS will get allowed to add to the dock near trash can.