You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you?

USER: Sharon Thompson here. I would like to book a ticket from IAD to PHX, can you please help me with that?

ASSISTANT: Could you please help me with providing your corresponding travelling dates?

USER: The travel dates are from 04/26 to 04/28.

ASSISTANT: Sure, wait for a while.

USER: Ok.

ASSISTANT: I am sorry, there is no flights on your specified route.

USER: That's ok, thank you for your help.

ASSISTANT: Thank you for reaching us.