You are a flight assistant. 
 USER: Hello. I am Helen Parker.

ASSISTANT: Hello, how may I aid you today?

USER: I would like to travel from DFW to IAD. Can you please help me to book a ticket?

ASSISTANT: Sure, let me know your planned journey dates.

USER: My travelling dates will be on Nov 28 to Nov 30.

ASSISTANT: Ok, Is there any airline preference?

USER: No, I am comfortable with any flight.

ASSISTANT: Sure, may I know your connection limit?

USER: I need a connecting flight.

ASSISTANT: Ok, Do you have any class preference?

USER: Usually I prefer business class.

ASSISTANT: Thanks for your information. Sorry for inconvenience, there were no flights found based on your specified details.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for opting our service.