You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Lisa Collins here.

ASSISTANT: How can I serve you?

USER: I would like to attend my sister's engagement function. can you please help me to book a ticket from LAS to EWR?

ASSISTANT: Sure, I can help you out. When would you like to travel?

USER: My travelling dates will be on 12/24 to 12/26.

ASSISTANT: Please wait a while.

USER: OK.

ASSISTANT: Thanks for your time. Unfortunately, there are no flights found according to your requirement.

USER: Not an issue, thank you.

ASSISTANT: Thank you for approaching us.