Transformer\ListingSuitabilityCollection::transform() not instance of \Entity\ListingSuitabilityCollection

[CreativeNative]

I get the following Error when I try to post a ListingSuitabilityCollection

[Thu Apr 28 01:31:05.593975 2016] [:error] [pid 28824] [client 79.36.160.185:65504] 
PHP Catchable fatal error:  Argument 1 passed to
Traum\\Transformer\\ListingSuitabilityCollection::transform() must be an instance of
Traum\\Entity\\ListingSuitabilityCollection, 
instance of Traum\\Entity\\ListingSuitability given,
called in 
/var/www/ferienhaussizilien.de/trunk/vendor/league/fractal/src/Scope.php on line 338 
and defined in
/var/www/ferienhaussizilien.de/trunk/vendor/aferalabs/traum/src/Transformer/ListingSuitabilityCollection.php on line 19

My code looks like following:

$suitability = [
    [
        Entity\ListingSuitability::SUITABILITY_ID        => Enum\Suitability::NON_SMOKERS,
        Entity\ListingSuitability::SUITABILITY_STATUS_ID => Enum\SuitabilityStatus::NOT_ALLOWED
    ],
    [
        Entity\ListingSuitability::SUITABILITY_ID        => Enum\Suitability::FAMILIES,
        Entity\ListingSuitability::SUITABILITY_STATUS_ID => Enum\SuitabilityStatus::ALLOWED
    ], 
    [
        Entity\ListingSuitability::SUITABILITY_ID        => Enum\Suitability::DOGS,
        Entity\ListingSuitability::SUITABILITY_STATUS_ID => ($rental->getEqpets()) ?
            Enum\SuitabilityStatus::ALLOWED : Enum\SuitabilityStatus::NOT_ALLOWED
    ],
];

$suitabilityCollection = Entity\ListingSuitabilityCollection::fromArray($suitability);

$responses['suitability'] = $client->createListingResource()->postSuitabilities(
    136390,
    $suitabilityCollection
);