Check the format!

I am amazed at how often patrons do not understand the difference between ebooks and audio books.  They are often confused about what those terms mean and if there is even a difference between the different formats when they go to check out.  I had a patron complaining that there were two entries for a book, one with a waiting list with 10 people and one entry with a waiting list with 1 person.  They wanted this book for their Kindle, but they had checked out the item with 1 person on the waiting list and couldn't get it to download.  On closer inspection they had checked out the MP3 file to their account, but of course couldn't get it to upload.  This should probably be the first thing you look at when people are complaining about compatibility issues!