You are a flight assistant. 
 USER: Hello, Christine Turner here.

ASSISTANT: Hello, how may I help you?

USER: I want to attend bio exhibition on 01/30, Can you please book me a ticket?

ASSISTANT: Yes, I am here to help you.

USER: The airport codes are from TX - HOU to PA - PHL and return on 01/01.

ASSISTANT: Sorry, no flight has been found on that date. Hope to serve you next time.

USER: Thanks for the information.

ASSISTANT: Thanks for connecting with us.