mgoblue has a good suggestion up there, and it was something I wanted to try with my transfer kit (but haven't found the time to try).
volsman: It's really hard to help you without more information about what you did and what exactly isn't working. Let's answer some simple questions to help figure this out. Which program did you use to transfer the rosters? Xplorer or Xchange? If you boot to the 360 dashboard, can you see the roster file using the System blade? If the answer to the last question is yes, try what mgoblue suggested. However, if you can't see the rosters with the dashboard, we can surmise that you simply copied the files over incorrectly.