I've been trying to enable AT&T hotspot using this source. I have had no luck. I used https://www.wireless.att.com/support_static_files/KB/KB517.html and http://tether.com/apn-settings to change the preferences.plist. I also tried changing the username and password. I only changed the 32-bit type-masks (32791 & 32790), the first and fourth. Any suggestions?