Calling $this->forward() results in blank page (but no error)

I try to use forward in my action class after a validation back to my action in special cases.

This works in another part of my application.

$this->forward('mymodul', 'actionx');

But when I execute this Action I only receive a blank page; in the symfony log is a forward message to my action the last entry.

No error on screen nor in my apache logs.

When I use Redirect it works, but I lose all my request parameters.

$this->redirect('mymodul/actionx')开发者_JAVA技巧;

Has anyone any suggestions?