Windows 7/WMP12 : wdtvlive not seen in: Media Streaming Options->Show devices on :

I try to make my Windows 7 Ultimate pc a DNLA server (with Windows Media Player 12) but until now without success.

I configured Media Streaming with WMP 12 but at the Network and Sharing Center -> Media streaming options-> Show devices on: my wdtvlive (and other xp-systems) does not show up.

In the explorer under Network they are all visiable.

Network shares on the Windows 7 pc are accessable from the wdtvlive.

Turning off the firewall has no effect.

Any ideas? TIA.

Dump WMP and use WMS (Wild Media Server)