You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am George White. I need to attend a meeting with my client at Washington. So, please reserve me a flight ticket to reach DCA.

ASSISTANT: Sure, tell me your travel dates please?

USER: My planned journey dates are 02/26 and 02/28.

ASSISTANT: Now please let me know your source airport code please?

USER: I would like to board from Denver, DEN.

ASSISTANT: Thanks for providing flight details. But I am sorry to inform you that there are no flights found with your flight details.

USER: It's ok, no problem. Thank you for the information.

ASSISTANT: Thank you.