Quick PHP script question

I'm trying to add the following script to my wordpress blog, however I keep getting a parse error. Any ideas on what's wrong here?

<?php 
if ( (is_single('121')) || (is_single('409')) )
{
echo '<a href="http://www.investortrip.com/ccount/click.php?id=23" target="_top">
<img src="http://www.lduhtrp.net/image-2160939-10468653" width="336" height="280" alt="" border="0" /></a>';
}
else {
<?php 
if (preg_match('/^http:\/\/(\w+\.)?(google|msn|yahoo|aol)\./',$_SERVER['HTTP_REFERER']) == 1) { ?>
<?php include 'adsense-combo.php'; ?>
<?php } ?>
} ?>

Code (markup):

Thanks

 

<?php 
if ( (is_single('121')) || (is_single('409')) )
{
print '<a href="http://www.investortrip.com/ccount/click.php?id=23" target="_top">
<img src="http://www.lduhtrp.net/image-2160939-10468653" width="336" height="280" alt="" border="0" /></a>';
}
elseif (preg_match('/^http:\/\/(\w+\.)?(google|msn|yahoo|aol)\./',$_SERVER['HTTP_REFERER']) == 1) 
{ 
include 'adsense-combo.php'; 
}
?>

PHP:

I have not tested this but this is the way it should be. Your mistake was to not end php tag. and restarting without ending it.

 

Thanks so much. I really want to learn more PHP so I can avoid those mistakes in the future. Where can I find a thorough tutorial?

 

no probs.. try http://www.w3schools.com/php/default.asp basic help would be here..