<#list List as list>
          <tr>
           <td class="span1">${list.id}</td>
            <td><a href="courses/${list.id}.html">${list.name}</a></td>
             
                        
             <#if   abilitySubscribe=="true" && CurrentUser?seq_contains(list.attendee)>  .. в этой строке
            <td>
              <a class="btn btn-mini" href="courses/${list.id}/attend.html">Attend</a>
            </td>    
            
            <#elseif   abilitySubscribe=="true"  >
            <td>
              <a class="btn btn-mini" href="courses/${list.id}/subscribe.html">Subscribe</a>
            </td>
            <#else>
             <td> </td>
            </#if>