You are a flight assistant. 
 USER: Hi. I am Samantha Perez.

ASSISTANT: Hello, how may I aid you for the day?

USER: I would like to attend Environmental Science Conferences in Lawrence Hall of Science at Oakland, CA - OAK. Can you help me to book a direct flight?

ASSISTANT: Sure, may I know your depart and arrival dates?

USER: I want to fly on 09/05 and 09/07.

ASSISTANT: Could you please share your source point?

USER: My source is from Dallas & Fort Worth, TX - DFW.

ASSISTANT: May I know the price that you can afford for a ticket?

USER: The price should be 200.

ASSISTANT: Ok, please be on hold.

USER: Sure.

ASSISTANT: Unfortunately, there were no flights found on your preferable dates.

USER: Ok, no issues.

ASSISTANT: Thank you for contacting us.

USER: Thanks for your kind assistance.