Most likely it was not in English, or it was a PDF attachment.

Tickets are best parsed in English, when done from messages with no PDF attachments, and when linked to a Gmail account whether the e-ticket is sent from Gmail or not. We are working on providing an algorithm to address this.

You can also enter the sender's email (airline, travel agency etc) in this form to help us support it in the future.

How to connect your Gmail account?