You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you today?

USER: Dennis Wilson here. Can you please book a flight ticket from HOU to SFO?

ASSISTANT: Sure, I will help you to book a flight. Can you please provide me your travelling dates?

USER: Sure, my travelling dates are from 07/05 to 07/07.

ASSISTANT: Please give me a moment.

USER: Ok.

ASSISTANT: Sorry, no flights are available on your route.

USER: No problem, thank you for your information.

ASSISTANT: Welcome, have a nice day.