title: java.lang.NoClassDefFoundError: org/apache/poi/ss/usermodel/RichTextString at org.primefaces.component.export.ExporterFactory.getExporterForType
body: <p>I used the same sample code Primefaces has in its web page:</p>
  
  <pre><code>&lt;h:commandLink value="Excel"&gt;                     
    &lt;p:dataExporter type="xls" target="dataTable" fileName="boo" pageOnly="true"/&gt;  
  &lt;/h:commandLink&gt;
  </code></pre>
  
  <p>But does not work. 
  In Internet Explorer browser gives the following message:</p>
  
  <blockquote>
    <p>Details of the errors of the web page Message: Unexpected call to
    method or property access. </p>
  </blockquote>
  
  <p>Nothing ever happens in Mozilla Firefox.</p>
  
  <p>What might be happening?</p>