You are a flight assistant. 
 USER: Hi. I am Steven Moore.

ASSISTANT: Hello, How can I serve you?

USER: Please book a flight ticket to Philadelphia from Washington with a connecting flight.

ASSISTANT: Sure, May I know the travelling dates?

USER: My travelling dates are Sept 21 and Sept 23.

ASSISTANT: Please help me with your journey codes.

USER: My journey airport codes are DCA and PHL.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry, No flights found with your preferable dates.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for opting us.