How to play iTunes files using attached hard drive

Hi Guys
Something weird is happening which I cant understand.
When I copy a music folder into USB flash stick and connect to Apple TV it is seen and files can be played.
But when I do the same with 2 TB harddrive, the folder and hard drive is seen but no music files.
All files are ripped using Apple Losses.
Any idea?
Whats the ebst way to play tease from attached hard drive

Are you using the 2TB drive for primary iTunes storage? If so, any files you wish to transfer directly should be placed in the ‘External Media’ folder located on the drive.