You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: Have a client meeting in Denver, DEN from Oakland, OAK, can you book it?

ASSISTANT: Ok, may I know your trip dates?

USER: Yes, my travel dates are 11/17 and 11/19.

ASSISTANT: Ok, may I know your name?

USER: My name is Dennis Green.

ASSISTANT: Sorry, no flights found on your dates to reserve your ticket.

USER: That's ok. Thank you.

ASSISTANT: Most welcome.