Hello and welcome to the Mikrotik forums!
Here are a few things to try....
>You definitely need to upgrade to the latest version of ROS 5.2
>Make sure to upgrade the hardware firmware too!
>Make sure you're using either NStreme or NV2
>Once you've got that done - start experimenting with different channels and above / below control settings
My recommendation would be to get everything working on a 20mhz channel first (HT Extension Channel: Disabled) then start trying above / below control.
I have a post that was written for the SXT's but the settings (except for the TX power notes)....should apply in your case as well:
http://www.wispforum.net/entry.php?5-Ho ... ode-Part-I
http://www.wispforum.net/entry.php?6-Ho ... de-Part-II
Let us know your results!