keys

Hey,

I'm trying to use keys as variables in my DITA project, but I can't figure out how to insert a "variable" in a topic using keys?

This is what my dita map looks like:

<map xmlns:ditaarch = "http://dita.oasis-open.org/architecture/2005/">

     <title>Product variables</title>

          <keydef keys = "product_name">

               <topicmeta>

                    <keywords>

                             <keyword>Sample Product Name</keyword>

                    </keywords>

                  </topicmeta>

             </keydef>

</map>

This is what the topic looks like but nothing happens

<concept id = "id144FF0W0FFP"

    xmlns:ditaarch = "http://dita.oasis-open.org/architecture/2005/">

<title>General description</title>

     <conbody>

          <p><keyword keyref = "product_name"></keyword> is a great product.</p>

     </conbody>

</concept>

Can anyone help me?