$output_cache.= $oFCKeditor->Create(); wont work :-(

I found a way to solve the problem:

<?php
$output_cache="Here comes the Editor:<br />\n";
ob_start();
$oFCKeditor->Create();
$output_cache.= ob_get_contents();
ob_end_clean();

echo $output_cache;
?>

This (ob_start) caches all the output. With ob_get_contents i can read the cached output into a variable. With ob_end_clean the caching will stopped and the cache will be deleted...