You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Scott Carter here.

ASSISTANT: How can I assist you for today?

USER: I am looking to book a plane ticket from DCA to HOU.

ASSISTANT: That's nice. Could you provide me your dates of travelling?

USER: My preferable travelling dates are from 10/04 to 10/06.

ASSISTANT: Give me a second, I will get back to you.

USER: Ok.

ASSISTANT: Sorry to inform you that there is no flight service provided in this route on your requested dates.

USER: It's ok. Thank you.

ASSISTANT: Thank you for choosing us.