Default [Q] Bought the SM-N900 for use in the US, did I mess up?

Basically Ive had the phone for over a month now and the connection issues have been constant. The carrier I use is Straight Talk. I got a new SIM card. Ive tried every APN setting it seems. And I cannot get any help. Did I plainly just mess up and by the wrong version of the phone I needed?
http://fp.profiles.us.playstation.com.s3.amazonaws.com/41/191/vicmora5.png?1294864322863