Why I get an error message in TYPO3 Extbase on the second time?

Question

I write an extension and use TYPO3 8.7 extbase. When I clear all cache my extension works only by the first Page visit, the second page visit get this error message:

Cannot create empty instance of the class "Pit\PitExt\Domain\Model\Settings" because it does not implement the TYPO3\CMS\Extbase\DomainObject\DomainObjectInterface.

Where is the Problem? On the first Visit it implement the interface, on the second time not?

Thank you for any help.

Answer 1

Sorry, my mistake. I had an upper / lower case problem. It is not "Pit\PitExt\Domain\Model\Settings" its "Pit\Pitext\Domain\Model\Settings". Now it works.