I have Prem. Elements 12. I am trying to add audio media. I know where the audio files are located (using GET INFO while in iTunes), and when I try to add certain audio files, some are accepted and some are not. In one case, when I opened a particular folder, the song was not listed, even tho' the song is there when using Windows Explorer. This happens with mp3 and mp4 and just wav files. Some audio are accepted, most are not. I get that codec is not installed error message, too.