You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: Can you aid me to book a flight ticket from SFO to IAH?

ASSISTANT: Sure, may I know the travelling dates?

USER: My trip dates are Apr 21 and Apr 23 respectively.

ASSISTANT: Do you have any connection limit?

USER: I prefer for connecting flight.

ASSISTANT: Are there any other requirements?

USER: No.

ASSISTANT: May I know your name?

USER: Barbara Carter here.

ASSISTANT: Please wait a minute.

USER: Ok.

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

USER: Thank you.

ASSISTANT: Thank you for opting us.