Matrix-field with a category-field to output category-title on single entry page Me and categories, always giving trouble :)

On blogs, we are using a matrix field and in one of the matrix-types, I have a category field.
This is to output the title of the category.

{% extends "matrix/default" %}
 {% block blockContent %}
 &lt;div class="row"&gt;
  &lt;div class="col flexcntr"&gt;
    {% set merk = block.merkNaam %}
    {{ merk.title }}
  &lt;/div&gt;    
 &lt;/div&gt;
{% endblock %}


The outcome is empty ...

What do I miss?
Nevermind, the problem is solved.

I just need to loop over the categories.

{% extends "matrix/default" %}
{% block blockContent %}
&lt;div class="row"&gt;
    &lt;div class="col flexcntr"&gt;
        {% for merk in block.merkNaam %}
            {{ merk.title }}
        {% endfor %} #}
    &lt;/div&gt;  
&lt;/div&gt;
{% endblock %}