Fatal error: Call to a member function on a non-object

I am getting the following error on my pages when I try to insert data. I am new to writing a plug-in and have run out of ideas on how to correct this one. Any help would be greatly appreciated. Here is my code….

global $wpdb;

$table_name = “wpv_table”;

$payer_email = “[email protected]”;
$first_name = “Lucy”;
$last_name = “Smith”;
$txn_id =”5555″;
$payment_status = “Completed”;
$custom=”Ashley Stewart – Hidden on homepage”;
$auction_buyer_id = “”;
$auction_item_number = “”;
$item_number = “47”;
$key = “47”;
$sku = “”;

$insert = “INSERT INTO ” . $table_name .
” (payer_email, first_name, last_name, txn_id, payment_status, custom, auction_buyer_id, auction_item_number, item_number, key, sku, datetime) ” .
“VALUES (‘” . $wpdb->escape($payer_email) . “‘,'” . $wpdb->escape($first_name) . “‘,'” . $wpdb->escape($last_name) . “‘,'” . $wpdb->escape($txn_id) . “‘,'” . $wpdb->escape($payment_status). “‘,'” . $wpdb->escape($custom) . “‘,'” . $wpdb->escape($auction_buyer_id) . “‘,'” . $wpdb->escape($auction_item_number) . “‘,'” . $wpdb->escape($item_number) . “‘,'” . $wpdb->escape($sku) . “‘,'” . time() . “‘)”;

function insert_order($content) {
$results = $wpdb->query( $insert );

}

add_filter(‘the_content’, ‘insert_order’);