I have a Captivate with firmware 2.2 build Froyo.uckb1 which won't work with pptp over 3g. I know pptp is configured correctly as it works fine if I connect to wifi. I also know pptp makes it to my corporate server with 3g as I get a password error if I use the wrong password. But if I used the correct login info, it says "connecting" for awhile and then times out with an "Unable to connect to network" error. Something on the phone (or 3g service) is blocking the connection from being completed.