We need to see if the number of rows returned by $listing_split is greater than zero (my guess is it isn't) so try adding this 'die' line....
Code:
die('I see ' . $listing_split->number_of_rows);
if ($listing_split->number_of_rows > 0) {
  $rows = 0;
  $listing = $db->Execute($listing_split->sql_query);
  $extra_row = 0;
  while (!$listing->EOF) {
    $rows++;

    if ((($rows-$extra_row)/2) == floor(($rows-$extra_row)/2)) {
      $list_box_contents[$rows] = array('params' => 'class="productListing-even"');
    } else {
      $list_box_contents[$rows] = array('params' => 'class="productListing-odd"');
    }
...then go directly to this link....
Code:
http://www.bigandtallwarehouse.com/Jeans?sort=0&fltSizes[]=80x32
If you see 'I see 0' then $listing_split is zero which is why you're getting no products listed.
We'd then need to look at file 'includes/classes/split_page_results.php' to see why $listing_split has returned no rows.
Did you upload the 'split_page_results.php' file supplied in the distribution or did you add the changes manually?

I'll not be around now for just over a week so good luck getting this working. If you're still struggling we'll try again when I'm back