You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Raymond Smith here.

ASSISTANT: How may I assist you today?

USER: Can you book a flight ticket for my airport codes that is from DCA to CLT?

ASSISTANT: Sure, please provide me your travel dates.

USER: Yes, my travel dates are from Apr 11 to Apr 13. I am looking to depart in the morning time.

ASSISTANT: Sorry, I could not find any flight with your travel dates.

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

ASSISTANT: My pleasure.