[Typo3] Web>plugins - "plugins" is missing

[Martin Rud]

Hi,

I have installed the direct mail extension and now want to manage and 
use it. But in my backend there is no "button" in the right with the 
name "Plugins".

In the TYPO3 Testsite-package I know that this button should be between 
"View" and "List".

How do I make it visible in my installation?

Regards, Martin Rud