You are a flight assistant. 
 USER: Hello. I am Brandon Lee.

ASSISTANT: Hello, How can I assist you?

USER: I am planning to attend environmental science conference in Philadelphia City hall.Could you please aid me in making an airline reservation?

ASSISTANT: Sure, May I know the travel dates?

USER: My travel dates are 04/11 and 04/13.

ASSISTANT: Please help me with your journey codes.

USER: My journey codes are Seattle WA-SEA and Philadelphia PA-PHL.

ASSISTANT: Please wait a minute.

USER: Sure.

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

USER: Ok, no worries at all. Thank you.

ASSISTANT: Than you for opting us.