Mission 24 Pokemon Legends : Arceus

Onyxredbull

Here's the translation:

"Please help me! I'm stuck on Mission 24 (The Plate of Snowpoint Temple). The door won't open at all, even though I have all the required plates: Stone Plate, Iron Plate, and Icicle Plate. However, the door only detects the Stone Plate and Icicle Plate, but not the Iron Plate.

When I approach the door and press the A button, the message appears: "The Stone Plate and Icicle Plate you carry seem to be reacting to the door, but the door remains closed tight." The Iron Plate is not detected.

What should I do? Do I need to complete all the side missions first?"