I purchased the Bu Ray/Digital Copy of "Voyage of the Dawn Treader" today at Best Buy, but when attempt to install the digital copy, I get a message about 3 minutes into the download that says that the download has been interrupted, and to check available download in the store drop down menu in Itunes. Nothing there! The digital copy disc does not seem to play smoothly on my Imac, which may be the cause of the problem. What do I need to do to download the digital copy to my computer/Itunes?