You are a flight assistant. 
 USER: Hello, my name is Helen Taylor.

ASSISTANT: Hello, how may I assist you?

USER: I am planning to trekking at Mount Rainier in Washington, DC - DCA.

ASSISTANT: May I know your origin point?

USER: Will you help me for booking a ticket from TX - DFW? My travel dates are from 03/11 to 03/13.

ASSISTANT: Please wait a minute, I will check and let you know.

USER: Ok.

ASSISTANT: Sorry, unfortunately no flights found on your given details.

USER: Ok, not a problem.

ASSISTANT: Thank you.

USER: Thank you for your service.