yeild return new WaitForSeconds doesn't work

public class GoldPerSec : MonoBehaviour {

public UnityEngine.UI.Text gpsDisplay;
public Click click;
public ItemManager[] items;

void Start()
{
    StartCoroutine (AutoTick());
}

void Update()
{
    gpsDisplay.text = GetGoldPerSec () + " gold/sec";
}

public int GetGoldPerSec()
{
    int tick = 0;
    foreach(ItemManager item in items)
    {
        tick += item.count * item.tickValue;

    }
    return tick;
}

public void AutoGoldPerSec()
{
    click.gold += GetGoldPerSec();
}

IEnumerator AutoTick()
{
    while(true)
    {
        AutoGoldPerSec();
        yeild return new WaitForSeconds(1);
    }
}

}

Because it should be spelt yield, not yeild.