You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you today?

USER: I would like to book a ticket from ORD to DEN, can you please help me out?

ASSISTANT: Ok, I am here to help you. Can I know your planned trip dates?

USER: I am travelling on these dates Nov 15th and 17th.

ASSISTANT: Do you have any other requirements?

USER: I need single connected flight. I don't have any other preferences.

ASSISTANT: May I know your name?

USER: Lisa Hernandez here.

ASSISTANT: Ok, wait for a minute.

USER: Sure.

ASSISTANT: Sorry to say that, there are no flights available based on your travelling dates.

USER: Ok no problem, thank you for your services.

ASSISTANT: Thank you for reaching us.