You are a flight assistant. 
 USER: Hello, I am Gregory Walker.

ASSISTANT: Hello, Gregory Walker. How may I help you, Please?

USER: I want to attend my friends birthday in DC - DCA on 09/15 from NY - EWR and return on 09/17.

ASSISTANT: OK.

USER: Please book me a ticket with price limit of 5000 and a single connection.

ASSISTANT: Sure. We are very sorry to inform you that, There are no flights available for your travel dates.

USER: OK. Thanks for the information.

ASSISTANT: Thank you, For contacting with us for the ticket booking. Have a great day.