clicking a div to check a checkbox

I'm testing a js function to check and uncheck a checkbox with a separate div which also changes color.

The following script works when the checkbox id is typed into the function manually, but when I try to pass it in as a parameter it doesn't work. Am I doing something wrong?

<form action="#">
    <input type="checkbox" id="joe" name="joe">

<div id="container" style="background-color: red; width: 200px; height: 200px;" onclick="selected(this, 'joe')"></div>

<script>
    function selected(elmnt, id2check) {
        var x = document.getElementById("id2check").checked;
        if(x == false) {
                elmnt.style.backgroundColor = "blue";
                document.getElementById("id2check").checked = true;
        } else {
                elmnt.style.backgroundColor = "red";
                document.getElementById("id2check").checked = false;
        }
    }   
</script>

UPDATE:

Ah, just figured it out. The tutorial I was basing it on used quotation marks on the passed value. I took those off and it works now. :)