There are a few reasons why some tracks might not have been copied to the phone. These possible reasons are listed below:
- The memory card might be full
- The memory card might be incorrectly formatted or corrupted – you may wish to try reformatting it (note that this will erase all of the files on your memory card, so you should back up any important data first)
- The original track might be missing or corrupted – check that you can play the track from iTunes, if the track is not playable from iTunes then it probably cannot be copied to your phone