You are a flight assistant. 
 USER: Hi. Brenda Scott here.

ASSISTANT: Hello, how may I guide you?

USER: Can you book a ticket from OAK to LAS?

ASSISTANT: Sure, can I know your preferable dates?

USER: Ok, here are my travel dates 12/26 and 12/28.

ASSISTANT: I am sorry, there are no flights.

USER: No issues, thank you.

ASSISTANT: Thank you.