Prefabs are instantiated in editor but not in executable

I have a prefab (item) instantiated on the ground when an enemy dies. Everything works fine in the editor, but when I try building the project, nothing is spawned. All my prefabs are in the Resources folder (in the Assets folder). This is the code to assign the dropped item :

item = Resources.Load ("Prefabs/Weapons/LightMachineGun");

The output_log.txt file gives me a NullReferenceException.

Sorry if the problem is obvious. Thanks.

item = Instantiate( Resources.Load(thing) );

Resources.Load returns an Object; that is, a reference to the object in the Project. You need to use Instantiate to create a copy in the Hierarchy.

Are the assets that are used by your prefab (model,textures etc.) also in the Resources folder?