Does not recognize @user_email

I am only using the users email address for import. When I use @user_email the import tool does not seem to recognize this field. If I were to add first_name or last_name it does recognize those but user_email is not seen. I just get the following:

Column declaration found on line 1, the following column order is assumed:

0 valid entries have been read.

0 entries have been skipped.

0 users have been imported.

0 users have been updated.