optical input no sound

[iwandigital]

I just bought Edifier m3600D THX certificate speaker there are optical input, the problem is I try to optical output with my computer GA-Z77-D3H MAINBOARD but no sound, please help.
should I use av receiver to turn optical cable to speaker?

 

[CountMike]

Did you set optical as default output in Windows > Control panel > Sound ?

 

[iwandigital]

Yes optical as default output
I see on device manager digital audio spdif is ready, work fine
on control volume I can see sound indicator is moving
Using Rca cables is work fine