WDS problem

I have a little problem, I configured 8 wds inteface, but occasionally when I reboot machine the tool winbox and console ( with command print) only show 6 or 4 wds interfaces, and before beginning again, they all were. What is the solution ? Have mikrotik some limitation regarding the number of wds interfaces ?

Thanks

What motherboard you useing to get 8 interfaces.

I have created 8 virtual interfaces wds, the problem is when i reboot again the router (router board 200 with 4 cards wireless 3 atheros and a prism) only show 4 or 6 wds interfaces, Why lose the others wds interfaces?

Thanks