Remember, that Omega doesn't support APs that are n-only, nor does it work at 5GHz. So you need to either slow down all of your other wireless devices by enabling b/g support, or set up a separate AP for the Omega (this is what I've chosen to do). Also, if your WPA uses TKIP, you can't use wifisetup, and need to edit /etc/conf/wireless manually.
Basically, wi-fi - like many other things - is a huge mess on the Omega.
I'm personally regretting buying one more every day, I've already scrapped the project I originally bought the Omega for, and instead used a Raspberry Pi Zero, a Hat and a bunch of other components instead. While the form-factor is bigger, and there are more separate pieces to manage, I was up and running within minutes, whereas with the Omega it took days to just learn why my Omega didn't respond to anything (through support I learned my Omega was apparently delivered with a faulty/missing firmware), and that was only the beginning of my problems, as I moved from re-flashing the board to actually connecting it to something.
Good luck with getting your Omega connected!