change order status in magento

gistfile1.php

<?php
	require_once 'app/Mage.php';
	umask(0);
	Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID);
	$userModel = Mage::getModel('admin/user');
	$userModel->setUserId(0);
	
	$from_date = $_GET['fdate'];
	$today = date("Y-m-d");
	
	try{
		$orders = Mage::getModel('sales/order')->getCollection()
		->addFieldToFilter('created_at', array('from' => $from_date, 'to' => $today))
		->addAttributeToFilter('status', array('neq' => Mage_Sales_Model_Order::STATE_COMPLETE));
		foreach($orders as $order){
			/*========================================================*/
			if($_GET['invoice'] == 'y'){
			
				if(!$order->canInvoice()){
					Mage::throwException(Mage::helper('core')->__('Cannot create an invoice.'));
					continue;
				}

				$invoice = Mage::getModel('sales/service_order', $order)->prepareInvoice();

				if (!$invoice->getTotalQty()){
					Mage::throwException(Mage::helper('core')->__('Cannot create an invoice without products.'));
				}

				//$invoice->setRequestedCaptureCase(Mage_Sales_Model_Order_Invoice::CAPTURE_ONLINE);
				//Or you can use
			   $invoice->setRequestedCaptureCase(Mage_Sales_Model_Order_Invoice::CAPTURE_OFFLINE);
				$invoice->register();
				$transactionSave = Mage::getModel('core/resource_transaction')
					->addObject($invoice)
					->addObject($invoice->getOrder());
				$transactionSave->save();
			}
			/*========================================================*/
			
			$order->setData('state', "complete");
			//$order->setState(Mage_Sales_Model_Order::STATE_COMPLETE, true);
			$order->setStatus("complete");
			$history = $order->addStatusHistoryComment('Order was set to Complete by our automation tool.', false);
			$history->setIsCustomerNotified(false);
			$order->save();
			echo "Order id - " .$order->getId() . 'has changed order status COMPLETED.';
		}
	}catch(Exception $e){
		echo $e->getMessage();
	}
?>