How to use POST statuses/update with a @mention?


For one of my projects, I’m trying to update twitter users status using POST statuses/update but at the same time also mention another user using @ so the other user can see it on his mentions tab. The status posts fine on the profile page but no matter what I try to mention other user be it @ or %40, it never works. In fact when I use @ the status wont even update. For example I’m trying to post this: @david have a look at this site its cool.

Any urgent help is greatly appreciated.