Why doesnt my gameobject get filled?

I am trying to create a select object script in unity.

What it should do is when i hover over an object it colors red (and it does) and when i press "1" the GameObject targetSelected will be filled with the object i am hover on on that moment. In a Debug.Log this all works fine, the targetHighlighted is filled.

When i press "1" however the targetHighlighted object is empty. It doesn't matter if i press it still on the object or away from it.

Ofcourse the code was more extensive to use it the way i want. But in this code is the problem, so i reduced it to this.

Can anyone help me why when I press "1" the the Debug.Log doesn't show the targetHighlighted?

Basicly why do the mouseenter and mouseexit log the right Object, and the setTarget function doesnt?

Thanks in advance.

 using UnityEngine;
 using System.Collections;

 public class TargetSelectionScript: MonoBehaviour {
 GameObject targetHighlighted;
 GameObject targetSelected;
 Renderer rend;
 Color initialColor = Color.white;
 Color selectedColor = Color.red;
 public GameControllerScript gameController;

 void Start() {

 }

 void Update() {
     if (Input.GetKeyDown("1")) {
         SetTarget();
     }
 }

 void OnMouseEnter() {
     SelectTarget();
 }

 void OnMouseExit() {
     ClearTarget();
 }

 void SelectTarget() {
         RaycastHit hitInfo = new RaycastHit();
         Physics.Raycast(Camera.main.ScreenPointToRay(Input.mousePosition), out hitInfo);
         targetHighlighted = hitInfo.transform.gameObject;
         rend = targetHighlighted.GetComponent < Renderer > ();
         rend.material.color = selectedColor;
         Debug.Log("Selected target: " + targetHighlighted);
     
 }

 void ClearTarget() {
     Debug.Log(targetHighlighted);
 }

 void SetTarget() {
     Debug.Log(targetHighlighted);
 }

}