"Could not be read" indicates the folder you are choosing "4048" does not have write permission in your operating system. SO change the permission to WRITE; or try a different destination folder in a different location.
The most common problem for "cannot be read" errors is a file system permissions problem on the destination folder.
Using Finder, make sure you have READ and WRITE access to the destination folder and to its parent.
I know this is going to sound very stupid but I went to finders it was like I had blinders on. I am doing this for my husband. I downloaded this Lightroom program and I hate it already. I have no idea how to change Read or write on this thing.