There are a handful of reasons a bonus does not apply to a bet. Work through them in order.
The game is not included. Each bonus has its own list of games or providers. Open the Promotions page, select your active bonus and check the eligible games. Bets on other games use your cash balance and do not count towards wagering.
Your bet is bigger than your remaining bonus balance. A bonus bet is paid entirely from the bonus balance; it never tops up from cash. Lower the bet.
The bet breaks the bonus's rules. Some bonuses have a maximum bet. Sports bonuses can have minimum odds (the sportsbook welcome bonus needs odds of 1.5 or higher).
The bonus was not activated. A deposit bonus has to be claimed on the Promotions page before you deposit. If you deposited first, that deposit did not activate it.
Another bonus is active. Only one bonus can be active at a time. A second one waits in the queue until the first is finished or cancelled.
It is a free spins offer. Free spins only work on the slot named in the offer.
Game won't load at all? See "A game won't load".
Still stuck? Message us with the name of the bonus and the game you are trying to play.