GetElementbyID fails to fire
<p>From my reading here I would expect this code to work, but it doesn't. I have tried two ways to add click events to a button called "lonext". Neither work. I'm not sure why this might be?</p>

<pre><code>window.onload = function() {

var goSC = function() { //go to the sucess criteria section
    document.getElementsByClassName("guidance1").style.display = "none";
    document.getElementsByClassName("guidance2").style.display = "";
    alert("button clicked");

//first try
document.getElementById("lonext").addEventListener("click", function() {
    goSC();     
    }, false);

//second try
document.getElementById("lonext").onclick = goSC;

}
</code></pre>
