Why is my Object not filled - unity3d

Question

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's targetHighlighted will be filled with the object I am hovering over at that moment. In a Debug.Log this all works fine, targetHighlightedis filled.
When I press "1" however the targetHighlighted object is still left empty. It doesn't matter if I press it while hovering over the object or away from it.
My full code is much more extensive than this. But this section of code contains the problem, so I reduced it to this.
Can anyone explain to me how come when I press "1" the the Debug.Log doesn't show the targetHighlighted or targetSelected?
Basically why do the mouseenter and mouseexit log the right Object, but the setTarget function doesn't?
using UnityEngine;
using System.Collections;
public class TargetSelectionScript: MonoBehaviour {
// Store the current selected gameobject
GameObject targetHighlighted;
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("Highlighted target: " + targetHighlighted);
}
void ClearTarget() {
Debug.Log(targetHighlighted);
}
void SetTarget() {
Debug.Log(targetHighlighted);
}
}

Answer 1

Because no key is registered under "1"
for this reason, you must resort to using the appropriate KeyCode,
if (GetKeyDown(KeyCode.Alpha1))
SetTarget();

Answer 2

Try these changes:
GameObject targetHighlighted;
Renderer rend;
Color initialColor = Color.white;
Color selectedColor = Color.red;
public GameControllerScript gameController;
[SerializeField]
private bool targetSelected = false;
void Start() {
}
void Update() {
if (Input.GetKeyDown("1") && this.targetSelected == true) {
SetTarget();
}
}
void OnMouseEnter() {
SelectTarget();
}
void OnMouseExit() {
ClearTarget();
}
void SelectTarget() {
RaycastHit hitInfo;
Physics.Raycast(Camera.main.ScreenPointToRay(Input.mousePosition), out hitInfo);
this.targetHighlighted = hitInfo.transform.gameObject;
rend = this.targetHighlighted.GetComponent < Renderer > ();
rend.material.color = selectedColor;
Debug.Log("Highlighted target: " + targetHighlighted);
this.targetSelected = true;
}
void ClearTarget() {
Debug.Log(this.targetHighlighted);
}
void SetTarget() {
Debug.Log(this.targetHighlighted);
}