There are a few reasons why you might not be able to place your live bet:

Temporary suspension: Some bets are temporarily suspended during certain game situations. For example, a "next goalscorer" bet might be paused during a penalty kick.

Bet closed: Once a bet's outcome is decided, it's permanently closed. For instance, an "over/under 0.5 goals" bet closes after the first goal is scored.

Scenario change: Live bets are dynamic and depend on the game's flow. If a specific scenario is no longer possible the corresponding bet will be removed. For example, a "Race to 20 Points" bet in basketball disappears once a team reaches 20 points.