It's more than that. Yes the folder containing the files must be shared, but they must be mounted and the file path to the folder thus mounted must be exactly the same as the file path stored in the container field.
Thanks Phil, It took me a while to get into the business to test it out. Basically they had been using a client to client solution as the server was having problems. once I served the program and relinked the files it worked, but they will have to relink all 500+ files.