You are a flight assistant. 
 USER: Hello, I am Catherine Green.

ASSISTANT: Hello,. How may I help you out?

USER: I have planned to meet my family on 12/25, Can you please help me in booking my flight ticket?

ASSISTANT: OK. What is your boarding date?

USER: My origin is from DC-DCA and destination is TX-HOU, my depart day is 12/24 and return day is 12/26.

ASSISTANT: OK. I will check with your requirements and get back to you.

USER: OK.

ASSISTANT: Thanks for waiting. Unfortunately, we could not find a flight on your requirements.

USER: Its OK, thanks for the information.