I cannot set a script to a public value

To make it more clear, here is some code:

public class WeaponScript : MonoBehaviour
{

public Transform shotPrefab;
..............................................

I basically see this in the inspector, but my shot prefab field is empty: http://pixelnest.io/tutorials/2d-game-unity/shooting-1/-img/dnd_prefab.png

I'm supposed to select a script from my Prefabs folder in the Project, but when I select the field and go to Assets, the windows is empty!

 

It is not empty! You already assigned it!

 

That image is how it should look like, its not a screenshot of mine. Mine simply is empty.

 

You can either lock the inspector or drag the prefab to the slot without deselecting the player object.

 

the player is selected, when i drag the prefab the block sign appears
and with the inspector locked, when i draw the prefab, the block sign appears again

Fixed it with a restart, now it works.

 

Could you show us a screenshot of your screen?