WDS Bridge works, but with errors

Hello,

i set up a wireless connection with two RB433
like in this description

http://wiki.mikrotik.com/wiki/Transparently_Bridge_two_Networks

The bridiging of the networks works. Devices on both sides are able to communicate
with the devices on the other side.
But i from each side i can’t reach the RB433 device on the other side.

I have no idea what i may have missed or misconfigured.

thanks for your help.

Dominik