Alfresco custom metadata templates

Question

I'm trying to display a custom type matadata template. This type extends cm:cmobject, like this:

<type name="tc:box">
    <title>Box</title>
    <parent>cm:cmobject</parent>
    <properties>
        <property name="tc:boxName">
            <type>d:int</type>
        </property>             
    </properties>
</type>

Following the official Alfresco documentation, I've declared the evaluators:

<bean id="tc.evaluator.isBox" parent="evaluator.doclib.action.nodeType">
    <property name="types">
        <list>
            <value>tc:box</value>
        </list>
    </property>
</bean>

And the metadata template:

<template id="tcBoxMetadataTemplate">
    <evaluator>tc.evaluator.isBox</evaluator>
    <line index="10" id="description" view="detailed">I AM A BOX</line>
</template> 

Everything in the same way I do with folders or content. I'm able to change the metadata displayed in custon types that extends cm:folder or cm:content, but not in this particular case.

Is there any limitation on adding new metadata templates or do I have to declare this custom type somewhere, maybe?

Thank you in advanced! Regards.