Expected argument of type "object, array or empty", "string" given in PropertyPathMapper.php

[msalsas]

Hello, I'm newer in symfony, so I'm sorry if my question is obvious. I've installed your HerzultForumBundle following the installing instructions and it seems that it is working, but when I try to create a topic or a post, the answer is:
Expected argument of type "object, array or empty", "string" given in /MiServer/transf/vendor/symfony/symfony/src/Symfony/Component/Form/Extension/Core/DataMapper/PropertyPathMapper.php at line 30

if (!is_array($data) && !is_object($data)) {
throw new UnexpectedTypeException($data, 'object, array or empty');
}

I've added to my routing file the next code:

forum:
resource: @HerzultForumBundle/Resources/config/routing/forum.xml
prefix: /forum
forum_category:
resource: @HerzultForumBundle/Resources/config/routing/category.xml
prefix: /forum
forum_topic:
resource: @HerzultForumBundle/Resources/config/routing/topic.xml
prefix: /forum

I'm not sure if I'm doing anything wrong. Do you know what could it be? I've wasted a lot of time trying to fix it. Thank you

[msalsas]

I solved it, but I changed two things before and I don't know wich of them has soved it.

1. I had used a "Usuario" class, instead of "User" class. I've changed it to "User" class.
2. I have installed the gedmo/doctrine-extensions.