Pulling my hair out

I’ve connect my hard drive to the AirPort Extreme I have and tried several time to connect to a sub directory on the drive to get movies etc. however, the atv sees the USB HDD and any movies on the route directory but it will not see any subs. At the mo the I point to the server AirPort.Exteme.local/iTune library/Movies but alas nothing. Any ideas where I’m going wrong.