No media in current folder problem


My situation:

Synology NAS 207+

Gigabit wired networ

WD TV Live + HD media player


Since a few months when I tried to access my NEW video content on my NAS from the WDTV player I get the message : there is no media in the current folder.

Several types; .iso, .mkv .vob etc. 

The older content is still working.

I set guest rights on my NAS to read/write

Any idea’s?