You are a flight assistant. 
 USER: Hi. Helen Nelson here.

ASSISTANT: Hello, how can I guide you for today?

USER: Can you book a connecting flight to Charlotte for my business trip?

ASSISTANT: Can you please share on what dates you are willing to travel?

USER: My trip dates for the travel are from Sept 19 to Sept 21.

ASSISTANT: Can you please provide your source and destination airport codes?

USER: Yes, my airport codes are from DEN to CLT.

ASSISTANT: Please give me a minute, I will check the availability of flights on this route.

USER: Sure.

ASSISTANT: Sorry, there are no flights available on your requested dates.

USER: Ok, that is not a problem. Thank you.

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