this code does work it just doesn't show up my iframe why?

<?php
$apt = isset($_GET['apt']) ? $_GET['apt'] : 'apt';
if ($apt=="KLU")
echo "Have a nice weekend!";
else
echo "<iframe name="ab_golf" class="mid" id="ab_golf" src="http://www.xxxxxxx.com/iframes/golf/<?=$apt;?>" longdesc="" vwidth="480" height="900" noresize="noresize" frameborder="0" scrolling="no" onload="window.scrollTo(0,0);"><a href="http://www.xxxxxxx.com/iframes/golf/<?=$apt;?>" target="_blank">Click here to view content of this frame</a></iframe>";
?>

the function in its original state

<?php
$d=date("D");
if ($d=="Fri")
echo "Have a nice weekend!";
else
echo "Have a nice day!";
?>

thanks!