RouterBoard 750UP + Unifi AP

Hi!

I have tried to read and learn as much as i can from the manual and from this forum but i haven’t had any success.
This is what i want to do:
https://docs.google.com/file/d/0B6LMVMzlErNncGNGV1p0RndaaVU/edit

I just want a single SSID with some WPA security, no guest access or hotspot.

I thought that this was an plug and play solution, just plug in the Unifi AP, it would get an IP and then i run the controller software and everything is fine.

This is the error message i got when i plug it in directly to the 750UP:
default offering lease 192.168.88.253 for 24:A4:3C:E6:40:31 without success

Do i need to change anything to let the Unifi AP get an IP-adress?

Thanks in advance!
Mikrotik Unifi.png