I replaced a working file, with the same file from another working web site, but the new file generates a HTTP 500 internal server error page.

The only difference in the new page are these lines:

$_SESSION['searched'] = $_GET['keyword'];
$prch = $_GET['p'];
if ($user_id == "") {
$new_temp = "themes/$user_theme/search_results1.htm";
}elseif ($prch == "1") {
$new_temp = "themes/$user_theme/search_results2.htm";
$new_temp = "themes/$user_theme/search_results.htm";
I'd like to learn the reason why these lines might be creating this error.