You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you at this minute?

USER: I would like to travel from DCA to OAK, can you please book my flight ticket?

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

USER: I would like to depart on Apr 28th and return back on Apr 30th.

ASSISTANT: Can I know your good name?

USER: My name is Scott Robinson.

ASSISTANT: Is there any other specifications?

USER: I am looking for a connecting flight.

ASSISTANT: Ok, please wait for a minute.

USER: Sure.

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

USER: Sad to hear that, thank you for checking.

ASSISTANT: Thank you for reaching us.