PHP随机广告不起作用？

<div id="leaderboardAd">
    <?php
        //THIS SCRIPT GENERATES A RANDOM AD.

        $randomAd = rand(1,2);

       switch($randonAd) {
            case "1":
                $adNumber = "/contributors.php";
                $pngNumber = "/images/contributorsAd.png";
            case "2":
                $adNumber = "http://www.cameronmontesano.com";
                $pngNumber = "/images/cameronmontesano-com.png";
            default:
                $adNumber = "/contributors.php";
                $pngNumber = "/images/contributorsAd.png";
        }
    ?>
    <a href="<?php echo $adNumber ?>">
        <img src="<?php echo $pngNumber ?>" width="720px" height="90px" /> 
    </a>
</div>

It only shows the default ad.

Perhaps if you spent less time sitting on your o key and actually looking at your code, you'd see this:

    $randomAd = rand(1,2);
          ^----
   switch($randonAd) {
                ^---- spot the difference.

Your switch statement uses $randonAd but the random variable you are setting is $randomAd.