Hi saraclare1,
This is hard to answer without more details.
Here are a few things I can think of ~
~~Occasionally, a sweeps will say that it does not accept certain emails, like hotmail or yahoo, for example. This is an exception, and not the usual case.
~~Did you double check your email address? If you are using a form filler, or copying and pasting, make sure you don't have anything like an extra space or extra "."
Hopefully other people will add their ideas and you will figure it out.