
In you blackberry, go to menu Option > Advance Option > TCP > and there's a blank field in APN. You should fill in this field based on your phone provider. If you have no idea about this you can ask for help provider support.
In Indonesia for Telkomsel user, your APN is : telkomsel, user: wap, pass: wap123. Then back to your tiny twitter, and voala ... work. GOod luck!