You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I am looking to book a flight ticket from CLT to DEN. Can you help me for that?

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: My travelling dates are Aug 15 and Aug 17.

ASSISTANT: Ok, could I have your name please?

USER: My name is Eric Lee.

ASSISTANT: Ok, do you need direct or connecting flight?

USER: I prefer to book a single connecting flight.

ASSISTANT: Ok, do you have any other specifications>.

USER: No.

ASSISTANT: Sorry, there is no flight on your requested travelling dates.

USER: That's ok, thank you for checking.

ASSISTANT: You are welcome.