You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How can I aid you?

USER: I am Matthew Wright. Can you please book a direct flight for me to attend a Global Environmental Seminar.

ASSISTANT: Sure, I can help you.

USER: Thank you.

ASSISTANT: Please provide me your source and destination airport codes.

USER: My source and destination airport codes are, PHL to HOU.

ASSISTANT: May I know your travelling dates?

USER: My journey dates on 05/22 and 05/24.

ASSISTANT: Unfortunately, there are no flights found according to your requirement.

USER: Ok, no issue. Thank you.

ASSISTANT: Thank you for reaching us.