if else script to control display of form in an iframe.

Hi all,

I have created a checkbox that clients can check or uncheck to control whether a vacancy enquiry form is displayed within the detail page.

I have tried to create an if else statement to dictate whether the form/iframe is displayed I can get it to display a test message based on 

<?PHP if ($advertisersRecord['show_vacancy_enquiry_form'] == "1") { echo"display form"}

else
{ echo "do not display form"; } ?>

however when i try to use this to control the display of the following code it does not work, the page simply doesn't load.

<script type="text/javascript">
document.write(unescape("%3Ciframe id=\"fb_iframe\" src=\"availability-request.php" + window.location.search + "\" width=\"100%\" height=\"1027\"allowtransparency=\"true\" scrolling=\"no\" frameborder=\"0\"%3E&lt;a href=\"availability-request.php\" title=\"availability-request\"&gt;Check out my CoffeeCup Form&lt;/a&gt;%3C/iframe%3E")); </script>
<noscript> <iframe
height="1027"
style="border:none; background:transparent; overflow:hidden;
width:100%;" id="fb_iframe" src="availability-request/availability-request.html">
<a href="availability-request.php" title="availability-request">Check out my CoffeeCup Form</a>
</iframe> </noscript>

In a nutshell I just want a simple if else script that says if the display box value is 1 show the form, else omit the code and carry on after the form section.  I have tried what I thought was required below but I am obviously missing something. Can anyone see where I am going wrong?

<?PHP if ($advertisersRecord['show_vacancy_enquiry_form'] == "1")
{
<script type="text/javascript"> document.write(unescape("%3Ciframe id=\"fb_iframe\" src=\"availability-request.php" + window.location.search + "\" width=\"100%\" height=\"1027\"allowtransparency=\"true\" scrolling=\"no\" frameborder=\"0\"%3E&lt;a href=\"availability-request.php\" title=\"availability-request\"&gt;Check out my CoffeeCup Form&lt;/a&gt;%3C/iframe%3E")); </script>
<noscript> <iframe height="1027" style="border:none; background:transparent; overflow:hidden; width:100%;" id="fb_iframe" src="availability-request/availability-request.html"> <a href="availability-request.php" title="availability-request">Check out my CoffeeCup Form</a> </iframe> </noscript>
}
else { echo "&nbsp;"; } ?>

Thanks in advance for any/all help provided.