Import Leads Reports Success with 0 records imported

Import Leads Reports Success with 0 records imported

I just tried to import 59 Leads. It looked like everything was working properly until I got this message.

Data Imported Successfully.

* No. of Records added: 0
* No. of Records updated: 0
* If you are unsatisfied with this import, you can rollback it at Import History

The file was not listed in the Import History.

Any idea what could be wrong?