You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I am Patrick Hernandez. I need to book a flight ticket from IAH to DEN, can you please help me for booking?

ASSISTANT: Sure, I am here to help you. May I know when you have planned to travel?

USER: I would like to travel on 09/19 to 09/11.

ASSISTANT: Wait a minute please.

USER: Sure.

ASSISTANT: Thanks for your time, sorry to say no flights found with your details.

USER: Ok, no problem.

ASSISTANT: Thank you for reaching us, have a nice day.

USER: Thanks for your information.