[TYPO3-mvc] view renderer ignores action argument

[g4-lisz at tonarchiv.ch]

Hi there,

in my action controller method i want to decide which template is going 
to be displayed.

This is because the layout looks a little bit different dependent of the 
search demand:

public function resultsAction(Tx_Myext_Domain_Model_SearchDemand $demand) {
[...]
     if ($demand->getSpecialDemands() !== NULL) {
         $action = 'resultsExtended';
         echo "Extended";
     }
     else
         $action = NULL;
[...]
     $this->view->attach(...);
     $this->view->render($action);
}

If the template "ResultsExtended.html" does not exists, the rendere 
complains about this.
If it does exist, the template "Results.html" is displayed in place of 
"ResultsExtended.html".

I.e. in the end it's always the default layout which is rendered.
Is there a solution to my problem?

Thank you,
Till