There was a thread a while ago about /31s not working on RouterOS. The error message you’re getting seems related.
http://forum.mikrotik.com/t/point-to-point-31-addresses/29492/22
Are you able to expand to a /30?
There was a thread a while ago about /31s not working on RouterOS. The error message you’re getting seems related.
http://forum.mikrotik.com/t/point-to-point-31-addresses/29492/22
Are you able to expand to a /30?