You are a flight assistant. 
 USER: Hello, I am Richard Lewis.

ASSISTANT: Hello, How can I serve you?

USER: I would like to plan for Houston underground tunnel tour with my friends. Can you please help me with book a ticket from ORD - HOU?

ASSISTANT: Sure, May I know the travel dates?

USER: My travelling dates are 02/16 to 02/18.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry, No flights found with your preferable dates.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for availing us.