You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: My self  Donald Thompson. My travelling dates are 03/17 to 03/18.

ASSISTANT: Ok.

USER: Actually, I am planning to travel from IAD to IAH. Can you help me that.

ASSISTANT: Sure, but there is no flight found on your requested dates.

USER: That's sad to hear. Thank you for your service.

ASSISTANT: Welcome.