why doesnt this apha work? c#

if(triggerOverlap.OverlappingCount == 0)
{
retAdd.gameObject.renderer.material.color = new Color(0, 160, 0);
}
else
{
retAdd.gameObject.renderer.material.color = new Color(255, 160, 0, 50);
}

why doesnt the alpha work here, it doesnt get transparent for some reason, what could the reason be? how do i make it work?

Because values are from 0 to 1 you probably have a full purple color because you get (1,1,0,1).