You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER:  I want to book a flight ticket to DFW. Can you please help me for booking from IAH?

ASSISTANT: Can I know your travelling dates?

USER: My travelling dates are on April 04 and 06.

ASSISTANT: Do you have any preference?

USER: My depart time is afternoon.

ASSISTANT: Let me know your name.

USER: My name is Charles Robinson.

ASSISTANT: Sorry, no flights found for your travelling dates.

USER: Ok, thank you.

ASSISTANT: Thank you.