Cant Figure Out Tethering

[supadoopa]

3GS 32GB running 3.0
I have carrier 5.0 (donwloaded from Muscle Nerd) I could not do it with 4.0 either, I just upgraded it today.
Itunes 9.1
I have modified the carrier.plist so I would have the Cellular Network Settings available. By adding "<key>AllowEDGEEditing</key>
<true/>" to my file and rebooting.

I have MMS working just fine. I however can not get tethering to work. I have installed benm and i GET the option to turn it on but when I plug it into my comptuer the toggle disapears! I remove benm and go back to it and it is there again but it keeps going away when I try to use it.

Am I doing something stupid or is this a known issue?

[supadoopa]

Come on guys, I cant be the only one that has this issue?

[frank1123]

have you tried the stealth ipcc?

Guide: MMS and Tethering working with AT&T on 3.0 iphone

just load it and go, don't mess with the network settings