I have found a hack to fix this but I am not happy with it.
in the file fihookes.class.php (/core/components/formit/model/formit/fihooks.class.php on line 306
the context key will get the context key of the file. but the contect key of the file is different then the context key set in the gateway file.
if I comment the $contextKey = $resource->get('context_key'); the right contect key will be set by the $this->modx->context->get('key');
If have made also a issue on the formit project
http://bugs.modx.com/issues/10000
greetings Thomas