You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I am Gregory Clark, I want to book a direct flight to Houston. Can you please help me in booking my flight ticket from Washington DC-IAD?

ASSISTANT: Sure, we are here to help you. Can you share me your travelling dates?

USER: Thank you. I want to start on 03/21, my return date will be on 03/23.

ASSISTANT: May I know your destination point?

USER: My destination point is at TX-HOU.

ASSISTANT: Ok, wait for a moment.

USER: Sure.

ASSISTANT: Thanks for waiting there are no flights found on your details.

USER: Ok, That's fine. I will go with other alternative.

ASSISTANT: Thanks for approaching us.

USER: Thank you for your effort.