I had the same problem:
I connected the external hard disk (hfs+ not journaled) to my mac, then updated all the disk permissions to read/write to all files on the diskand then it worked when connected to the wdtv via wifi
to do so:
connect the disk to the mac
- right clic (control click) on the disk icon on the desktop
- click Get Info
- unlock the bottom right lock on the info window by typing yr os x credentials (if applicable)
- give all the users (you - staff - everyone) read/write permissions
- then click on the gear icon and select all included elements
that should do it when you reconnect the hd to the wdtv.
let me know if that works for you
ciao
