DNS menu missing after upgrading to 11.5.1

All,

 

after upgrading to TMOS 11.5.1 (from 11.3.) I'm missing the new DNS menu on the main tab.

 

On a new machine with 11.5.1 pre-installed the menu item is there.

 

On the machine only LTM is licenced.

 

Where can I activate this menu item as I have some configurations requiring DNS cacheing profiles?

 

Thanks

 

René