CommandError: 'vidly.' is not a valid project name. Please make sure the name is a valid identifier

CommandError: 'vidly.' is not a valid project name. Please make sure the name is a valid identifier.

When I typed the command 'django-admin startproject vidly.', I got an error:

CommandError: 'vidly.' is not a valid project name. Please make sure the name is a valid identifier.
Can anybody help?