Your XML layout and Kotlin file might not be connected properly.

Common Fixes:

1. Check your Activity/Fragment Kotlin file: Ensure the package declaration is present at the top (e.g., package com.app_name...).
2. Check your XML layout: Verify the tools:context attribute is set (e.g., tools:context=".YourActivity").
3. Invalidate Caches and Restart Android Studio: Go to File > Invalidate Caches / Restart to clear any corrupted caches.

Missing these lines or having corrupted caches can break the connection between your code and layout.