You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself George Green from Houston.

ASSISTANT: Green, how may I assist you?

USER: I want to change my travel dates in my previous reservation, due to some problems I am unable to travel those dates so can you please help me with that?

ASSISTANT: Sure, let me check your reservation status in our database.

USER: Ok, thank you for your positive response.

ASSISTANT: Sorry Green, I have not found any reservation under your name in our database.

USER: Oh! It's ok no problem. Thank you for your information.

ASSISTANT: You are welcome.