You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I serve you today?

USER: I am Barbara Carter, I need a flight with one connection to Las Vegas to visit Bellagio Resort with my friends. Can you help me with booking?

ASSISTANT: Ok. May I know your airport codes?

USER: I will fly from Washington DC-IAD to Las Vegas NV-LAS.

ASSISTANT: To proceed booking I need your travelling dates.

USER: I like to travel on 05/21 and return on 05/23.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no flight found on your given requirements.

USER: Ok, thanks for helping me.

ASSISTANT: Thank you.