Hi Wei,
Feels like something is wrong with the calculation. Is TicketDate of type DateTime?
To debug this in your context just withdraw sequentially
- CurrentDateTime
- TicketDate
- CurrentDateTime - TicketDate
- ToTimeSpan(CurrentDateTime - TicketDate)
- ToTimeSpan(CurrentDateTime - TicketDate).Days
This will help you to understand where the error is and then fix it and implement the condition.
Also I would recommend using else statement instead of 2 if conditions.