You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I assist you?

USER: I want to book a flight ticket with the name Frank Edwards to Houston. Please help me out with a direct flight.

ASSISTANT: Sure, please let me know your airport codes.

USER: My source code is LAS and Dest code is IAH.

ASSISTANT: Can I know your travel dates please?

USER: My travelling dates are from 12/15 to 12/17.

ASSISTANT: Sorry for the inconvenience, there are no flights with your requirement at this moment.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you.