I keep getting this message while trying to make a character ...

The name you have chosen contains invalid characters.

Only alphanumeric (a-z, A-Z, 0-9), underscore ( _ ), period ( . ), and hyphen ( - ) characters are valid.
Please fix these errors and try again.

I have tried everything ... including one word names with no luck? I cannot figure out what the problem is. Anyone out there have an idea???