void Update()
{
mouse = transform.GetComponent().ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, 0.0f));

    if (Input.GetKeyDown(KeyCode.Alpha1))
    {
        ObjectInt = 1;
    }
    if (Input.GetKeyDown(KeyCode.Alpha2))
    {
        ObjectInt = 2;
    }
    if (Input.GetKeyDown(KeyCode.Alpha3))
    {
        ObjectInt = 3;
    }
    if (Input.GetKeyDown(KeyCode.Tab))
    {
        ObjectInt = 0;
    }

    //ShowObject and Instatiate if Mouse1 Pressed.
    ActiveObjects[ObjectInt].SetActive(true);
    ActiveObjects[ObjectInt].transform.position = new Vector2(mouse.x, mouse.y);
    if (Input.GetMouseButtonDown(0))
    {
        Instantiate(Objects[ObjectInt], new Vector2(mouse.x, mouse.y), Quaternion.identity);
        Debug.Log("Placed");
    }
}

After my change the “mouse” value the IF statements and anything else below doesn’t work, Though this is possibly very simple I can’t work it out, IF i move mouse below the if statements they work but still none of the important stuff below mouse, Hope someone can help.

Is mouse a Vector 3? Are you trying to place an object where the mouse is? If you make a variable Vector 3 mouse, and define mouse this way:

mouse = Camera.main.ScreenToViewportPoint(Input.mousePosition);

And then do this:

if (Input.GetMouseButtonDown(0))
     {
         Instantiate(Objects[ObjectInt], mouse, Quaternion.identity);
         Debug.Log("Placed");
     }

I think that would do the trick.

That isn’t tested in Unity, I don’t have access to it, but will in about 90 minutes, so let me know if that works for you, and if now, let me know what your errors are.