In explorers of sky Why cant you accept jirachis challenge?

In "Pokémon Mystery Dungeon: Explorers of Sky," you cannot accept Jirachi's challenge because it requires a specific condition to be met, namely the completion of the main story and the unlocking of certain post-game content. Jirachi's challenge is a special event that becomes available only after reaching a certain point in the game, making it inaccessible until then. Players must also ensure they have the necessary items and conditions to participate in this challenge.