Are you certain that your phone isn't "stealing" the connection? If your phone is near your computer, it tends to grab the connection to vivofit and prevent you from successfully pairing/syncing to your computer (although it should actually be uploading your data through your phone if this is the case). I'd recommend temporarily disabling Bluetooth on your phone when trying to pair/sync to your computer.
@HEATHERURBAN What model phone do you have? Are you on a PC or Mac? Garmin Express should be able to reliably connect to your vivofit. Be sure that your ANT stick is inserted fully into the USB port, that you have Garmin Express open, and that you are putting your vivofit into 'Pair' mode. If you are still having problems please provide as much detail as you can so someone cal help you. Alternatively, trying contacting Garmin Support:
www.garmin.com/contactsupport