Problems autoloading Zend view helpers

I mainly develop on Windows, and I have recently received an error a couple of times after deploying my Zend Framework applications to Linux boxes:

Fatal error: Uncaught exception 'Zend_Loader_PluginLoader_Exception' 
with message 'Plugin by name 'MyPlugin' was not found in the registry;

This error was odd as I knew the files existed with the correct permissions. I found the issue arises when I’ve been using a custom View object like so:

$view = new App_View();
$view->addHelperPath('/App/View/Helper', 'App_View_Helper');

$viewRenderer = new Zend_Controller_Action_Helper_ViewRenderer();
$viewRenderer->setView($view);

Where ‘App’ is my custom library within /library. The error is down to the preceding slash when adding the view helper path; the above should instead read:

$view->addHelperPath('App/View/Helper', 'App_View_Helper');

Although I would have thought this would have been automatically trimmed, removing the slash resolves the error.