Bug? Layer2 Loop with STP-Bridge and Bridge Control Protocol

Hi,

I want to deploy a Backup-Link between a wireless link. There is a small-bandwidth IP-connection from site A to site B with outgoing NAT. I have a L2TP-Server running at B and A is able to connect to B using the Backup-Line.

At each site there is a bridge interface with the according wireless interface as a member of the bridge. I added a PPP-Profile with the corresponding “Bridge” as described in http://wiki.mikrotik.com/wiki/Manual:BCP_bridging_(PPP_tunnel_bridging) to establish a layer-2 connection. After site A connected to site B using the L2TP-Connection the new interfaces will be added to the Bridge and I have a L2-link both on wireless and wired.

Unforunately I have a Layer2-Loop even if I activate STP or RSTP on the Bridge (backup-line is fully loaded).
Is that a bug?

Thank you,
Jann