You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I help you?

USER: I am Carol Parker. I am going to enjoy my holiday trip in the Redwood Regional Park with my colleagues, which is at Oakland. Can you book me a ticket within the range 500?

ASSISTANT: Sure, may I know your airport codes?

USER: Source is from IAH, and Destination is to OAK.

ASSISTANT: Do you have any connection limit?

USER: Yes, I need a connecting flight.

ASSISTANT: Let me know your travelling dates.

USER: I want to travel on 12/16, and need to catch return flight on 12/18.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no flights found on your given requirements.

USER: Ok, no issues. Thanks or the information.

ASSISTANT: Thank you for choosing us.