Php help – mystery code

I’ve been working for 4 days on what would take 10 minutes if I knew PHP better. It’s really simple, I bought a theme which has some positions for ads. One of them is set to appear between the two parts of each entry – (where “<!– more –>” comes into play)

First of all, I want to get rid of the damn thing. Here’s the relevant code from my single.php page:

<div class="entry">

<?php $single = sdac_triple_p_ad_code('single');?>

<?php the_content(''. $single.''); ?>
<?php edit_post_link();?>
<div class="tagzone">
<p class="tags"><span>Categorized:</span> <?php the_category(', ') ?><span class="sep">|</span><?php if (function_exists('sharethis_button')) { sharethis_button(); } ?></p>
</div>
</div>

That second line with the ‘sdac’ variable is obviously pulling the ad. But if I delete that line, not a blasted thing happens. Why? What in the world is it doing if it makes no difference if it’s there or not?

The source of that actual variable is coming from a custom widget. I can paste that too, but it would be great if someone could first decifer why in the name of god nothing whatsoever happens when I delete the line.

Many thanks!