Asset doesn't enter a script slot.

I want to drag an empty object which is called “ObjectManager” into a script slot

This is the script text I used to activate the script slot:

public GameManager gameManager;

When I try to drag “ObjectManager” into the script slot it doesn’t let me do so. But in my other scripts, dragging an asset to a script slot worked. This was that other script:

public PlayerMovement movement;

Why does this happen?

public has a capital P. change it to lower case and the spot for it should become available in the inspector. Im not sure which code editor youre using, but try and pay attention to the colors of stuff as well. For example in the code you posted above the “Public” for gameManager is purple and the “public” for movement is blue. This will give you an indication that although they bot say public they are going to behave differently (you want the blue).