Running makeUrl after $newpage->save()

<?php

$criteria = array(
    'alias' => $newalias,
	'parent' => $folder,
	'context_key' => 'act'
);
$document = $modx->getObject('modResource',$criteria);

if(!$document){

	// document does not exist
	// document generation required.
	
	$content = $modx->runSnippet('generateReport');
	
	// create report page by adding to criteria
	$criteria['content'] = $content;
	$criteria['published'] = 1;
	$criteria['template'] = 10;
	$criteria['menutitle'] = $readableDate;
	
	$pagetitle = 'Report page'; 
	$criteria['pagetitle'] = $pagetitle;
	$criteria['longtitle'] = $pagetitle;
	$criteria['richtext'] = 0;
	$criteria['publishedon'] = $datePoint;
	$criteria['createdby'] = 1;
	
	$newpage = $modx->newObject('modResource',$criteria);
	
	if($newpage->save() !== false){
		
		// this line was found at http://modxcms.com/forums/index.php?topic=46794.0
		$modx->cacheManager->clearCache();
		// hoped it would solve the problem but no! 
		
		$id = $newpage->get('id');
		// also tried calling the object all over again here, ie.
		// $doc = $modx->getObject('modResource',$criteria); 
		// $id = $doc->get('id');
		// but no joy..
		
		$content .= '<p>Page generated successfully: <a href="' . $modx->makeUrl($id) . '">'.$newpage->get('longtitle').'</a></p>';
		// LINK DOESNT WORK HERE, BUT IF I ECHO OUT $id ITS CORRECT! AND $newpage->get('longtitle') IS ECHOD OUT FINE TOO!
		
	}else{
		$content .= ' <p>Page generation failed</p>';
	}
	
}else{
	// document already exists
	// may as well use content from existing page
	$criteria = $document->toArray();
	$id = $criteria['id'];
	$content = $criteria['content'] . '<p>From existing page <a href="' . $modx->makeUrl($id) . '">'.$criteria['longtitle'].'</a></p>';
	// THIS LINK WORKS..
}
return $content;
?>