You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Can you please reserve me a flight ticket from  IAD to IAH?

ASSISTANT: May I know your desired travel dates please?

USER: My travel dates are Apr 29 and May 01.

ASSISTANT: Do you have any specifications?

USER: I need a connecting flight.

ASSISTANT: May I know your name please?

USER: I am Karen Garcia.

ASSISTANT: Sorry to say, there is no flight on your desired travel dates.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for opting us.