You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you out?

USER: I am planning to visit a Denver DEN to IAH. Can you make a reservation for me?

ASSISTANT: Sure, I will help you in booking the ticket. May I know your travelling dates please?

USER: Ok, my itinerary dates are on Nov 20 and return on Nov 22.

ASSISTANT: Can I know your name please?

USER: I am Dennis Miller.

ASSISTANT: Do you need any specifications?

USER: I need a single connecting flight.

ASSISTANT: Can I know your other preferences?

USER: No, thanks for asking.

ASSISTANT: Sorry, there are no flights found in our database.

USER: That's fine, no problem.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your help.