[TYPO3-mvc] backend-modul: sending mail -> template not found

[Johannes C. Schulz - EnzephaloN IT-Solutions]

Hello list!
Second problem going online with my new extension.
I wrote some actions for sending emails from the backend-module. Local my
extension worked, but online the template-file isn't found. I tried the
following codes:

$templateRootPath = '../'.$this->settings['templateRootPath'];
or
$templateRootPath = $this->settings['templateRootPath'];

But everytime a "not found" appears. 

How I have to assign the paths correctly in my backend-module??

Best regards
Johannes