C# access a generic list from another controller

Hello,

i am very new to unity and i cant solve this Problem:

 public class IodeController : MonoBehaviour {
 
     private PlayerController player;
 
     public ResourceModel IronModel;
     
     public void OnTriggerEnter(Collider other)
     {
         Gather(other);
     }
 
     public void OnTriggerStay(Collider other)
     {
         Gather(other);
     }
 
     public void OnTriggerExit(Collider other)
     {
         Debug.Log("Left Trigger");
     }
 
     public void Gather(Collider other)
     {
         player = other.GetComponent<PlayerController>();
 
         if (Input.GetButton("Interact"))
         {
             Debug.Log("i am In");
             var ironOre = new ResourceModel("Iron Ore", "Ore");
             Debug.Log(ironOre.Name);
             Debug.Log(player.Inventory.Count);
         }
     }
 }

this is the other class:

 [RequireComponent(typeof(CharacterController))]
 public class PlayerController : MonoBehaviour {
 
     public float moveSpeed;
     public float rotationspeed;
     CharacterController cc;
     AnimationCurve ac;
 
     private Animation aa;
 
     public List<ResourceModel> Inventory;
 
     // Use this for initialization
     void Start ()
     {
         cc = GetComponent<CharacterController>();
         aa = this.GetComponent<Animation>();
         Inventory = new List<ResourceModel>();
 
         Debug.Log(Inventory);
     }
     
     // Update is called once per frame
     void Update ()
     {
         transform.Rotate(new Vector3(0, Input.GetAxis("Horizontal") * rotationspeed * Time.deltaTime, 0));
         Vector3 forward = new Vector3();
 
         if (Input.GetButton("Vertical") && Input.GetButton("Sprint"))
         {
             aa.Play("run");
             forward = Input.GetAxis("Vertical") * transform.TransformDirection(Vector3.forward) * (moveSpeed * 4);
         }
         else if (Input.GetButton("Vertical"))
         {
             aa.Play("walk");
             forward = Input.GetAxis("Vertical") * transform.TransformDirection(Vector3.forward) * moveSpeed;
         }
         else
         {
             aa.Play("idle");
         }    
 
         cc.Move(forward * Time.deltaTime);
         cc.SimpleMove(Physics.gravity);
     }
 
     public void AddItem(ResourceModel model)
     {
         this.Inventory.Add(model);
         this.Inventory.ForEach(x => Debug.Log(x.Name));
     }
 
     public ResourceModel GetItem(string itemName)
     {
         return this.Inventory.SingleOrDefault(x => x.Name.Equals(itemName));
     }
 }

as you can see i want to set a new Instance of ResourceModel to the Inventoy, which i created on the Start function on the PlayerController. The INstance is there as aspected. But if i try to access it on the GatherOre Function the List is null.

Can somebody explain that? to me?