You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you at this moment?

USER: I would like to visit Space Center Houston. Can you help me in booking a ticket to Houston?

ASSISTANT: Sure, I am here to help you. Can you please provide your nearest airport codes of travelling?

USER: The airport codes are DCA and IAH respectively.

ASSISTANT: May I know your planned dates of journey?

USER: I am planning my journey on dates 02/23 and 02/25.

ASSISTANT: Wait a while please.

USER: Sure.

ASSISTANT: Sorry to inform you, there is no service available on this route with your provided dates.

USER: That's fine, thank you for the information.

ASSISTANT: May I know your name please for documentation purpose?

USER: Sure, my name is Kenneth Anderson.

ASSISTANT: Thank you for choosing our service.

USER: You are welcome.