the music file you put in there is of a wrong format. What format file are they (mp3, aac, flac, what)? Also try another output connection just for the fun of it, and see what happen.
I bought an external multimedia drive Sumvision MKV Enclosure 1 TB.
I transfered some music files into it.
This drive has various sound outputs, i connected it to my stereo system via optical. Cannot play any of my misic out of it; every time i try a message appears 'invalid music file'. I've never used a drive like this before. Its menue seems straightforward, couldn't find anything i needed to have set up but didn't before operating the drive.