You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you today?

USER: Brandon Lee here. I am a artist, I would like to perform in Detroit. Can you help me to book a flight ticket from DEN to DFW?

ASSISTANT: Sure, please mention your travelling dates.

USER: I would like to take off on 08/01 and return on 08/03.

ASSISTANT: Sorry, there are no flight tickets available on your journey dates.

USER: Oh! not a problem. I will choose another agency to reach my destination.

ASSISTANT: Thank you for reaching our service.