You are a flight assistant. 
 USER: Hello, I am Samantha Turner.

ASSISTANT: Hello, How can I help you?

USER: I want to go to business trip to Dallas & Fort Worth, TX - DFW on 12/05 from Washington, DC - IAD and return on 12/07. Can you please help me out in booking a ticket with a price limit of 200 and one connection?

ASSISTANT: Sure. Please wait a while,I will check and revert you.

USER: OK.

ASSISTANT: Thank you for waiting. Sorry, I did not found any flight based on your given preferences.

USER: Thanks for the information.

ASSISTANT: Thank you for contacting us.