I have ticket #400 but only 300 tickets have sold, is my ticket invalid?

No! Your ticket is still valid. When choosing a winner, we always enter the full range of tickets into the random number generator. If we draw a ticket that hasn’t been sold, we roll again until we find a winner! The parameters of the draw never change.

For example, if a competition has 400 total tickets and only 300 have sold, the range entered into the random number generator will still be tickets 1 to 400. The parameters don’t change if the competition hasn’t sold out.