V1.5.6.1 admin/model/sale/order Sort by Date Modified

There is faulty SQL in the admin ModelSaleOrder this prevents you from filtering orders by DateModified

admin/model/sale/order.php:623

Faulty code
<code>if (!empty($data['filter_date_modified'])) {
			$sql .= " AND DATE(o.date_modified) = DATE('" . $this->db->escape($data['filter_date_modified']) . "')";
		}</code>

The code should be
<code>if (!empty($data['filter_date_modified'])) {
			$sql .= " AND DATE(date_modified) = DATE('" . $this->db->escape($data['filter_date_modified']) . "')";
		}</code>