Vortexbox and Minimserver : "stopped"

[Ketalar]

My music files are on a Vortexbox (with Minimserver installed).
I can play them via Foobar on a local PC , but I would prefer to send them to the amplifier via an external DAC, instead of passing through the PC.
Minimserver interface seems correctly installed on the PC : the icon is green.
I have installed Foo_upnp :
- The upnp server sees the "Logitech mediaserver (vortexbox)" and the "Minimserver (vortexbox)".
- The UPNP controller sees my DAC and the other squeezeboxes.
- I can (right click) send a file to UPNP "Play on",e.g. DAC)
- But for any of them it says : "stopped".
Where is the problem (and its solution) ?

"To nobody, except those who will take pleasure here" (Franz Schubert, 1797-1828)