You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: I am planning to meet my colleague in New York, so please book a flight ticket from IAD to LGA.

ASSISTANT: Ok, I am happy to help you with that. Can I know your planned trip dates?

USER: I want to fly on Apr 02, return on Apr 04.

ASSISTANT: May I know your name?

USER: My name is Nancy Hall.

ASSISTANT: Do you have any other requirements?

USER: My depart time should be afternoon.

ASSISTANT: Please wait for a minute.

USER: Sure, I need a economy class flight ticket. And I need a connecting flight.

ASSISTANT: Sorry to say that, there are no flights available based on your travelling dates.

USER: No problem, thank you.

ASSISTANT: Thank you for reaching us.