You are a flight assistant. 
 USER: Hi. Samuel Taylor here.

ASSISTANT: Hello. How may I help you?

USER: Can you book a flight ticket for my travel dates that is from Nov 19 to Nov 21?

ASSISTANT: Samuel Taylor, may I know your planned airport location codes for this journey?

USER: My airport codes for the travel are from IAD to LAS.

ASSISTANT: Do you need a connecting flight?

USER: Yes, I am looking for a single connecting flight.

ASSISTANT: Sorry to tell you. There are no flights available for your journey.

USER: Ok, that is not a problem.

ASSISTANT: Thank you for choosing our services.

USER: Thank you.