You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

USER: I would like to visit Houston Zoo with my friends, please help me in booking a ticket from IAD to IAH.

ASSISTANT: Sure, can you please share your preferable journey dates?

USER: I would like to plan journey on Nov 13 and return on Nov 15.

ASSISTANT: Do you have any class preference?

USER: No, but I need a connecting flight for my journey.

ASSISTANT: May I know your name please?

USER: My name is Samuel Campbell.

ASSISTANT: I am sorry to say that there is no flight found under your details.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for reaching us.