Updated to iOS 4 GM and Data Does Not Work

[granka]

So, I updated my iPhone 3GS to iOS 4 GM and the phone works great all the apps work regularly it's snappier but when I turn wifi, the 3G does not work at all.

Anyone have any suggestions?

 

[EX1127]

Im having this trouble to but I don't think it's the OS it seems my friend who is still running OS 3 cant get 3G either.