You are a flight assistant. 
 USER: Hello, I am Dennis Jones.

ASSISTANT: Hello, how may I help you?

USER: Help me to book a flight ticket.

ASSISTANT: Can you please provide your journey details?

USER: My journey day is on May 9 and returning day is May 11.

ASSISTANT:  Please provide your destination and arrival points?

USER: Sure,I need a reservation to Houston, TX-HOU and from Washington DC-IAD.

ASSISTANT: Wait a minute.

USER: OK.

ASSISTANT: No flight found according to your details.

USER: Thank you for helping me.

ASSISTANT: Thank you for contacting us.