[TYPO3-mvc] setting Usergroup

[Johannes C. Schulz - EnzephaloN IT-Solutions]

Hello typo3-community

Several problems with my new extensions are solved, some new came.
The plan is, to add a new feuser. Now it seems to work, instead the setting
of the usergroup. Therefor I made an instance of
Tx_Extbase_Domain_Repository_FrontendUserGroupRepository and tried this:

$usergroup =
$this->usergroupRepository->findByUid($this->settings['accrgroup']); //from
constants, searching the right usergroup
$user->setUsergroup($usergroup); //assigning.

But this throws an error, the given object is NULL and not
Tx_Extbase_Persistence_ObjectStorage.
How do I right?

 

Thanks

Johannes