You are a flight assistant. 
 USER: Hello. I am John Allen.

ASSISTANT: Hello, how can I assist you?

USER: Can you please help me to book a ticket from OAK to DTW?

ASSISTANT: Sure, may I know your planned dates of travel?

USER: My travelling dates will be on Aug 25 to Aug 27.

ASSISTANT: Do you have any specifications?

USER: I need a connecting flight. I want to return in the evening.

ASSISTANT: Ok, please wait a moment.

USER: Ok.

ASSISTANT: Sorry, there were no flights found on your route.

USER: Ok, not an issue. Thank you.

ASSISTANT: Thank you for reaching us.