displaytag, spring, Nothing found to display - spring

Question

I have problems with sorting an table
and do not understand the displaytag...maybe they are easier ways to sort
using spring,hsql-db(later ms-sql)
I got "Nothing found to display" message from the id column
could someone explain me whats wrong?
<c:if test="${not empty msg}">
<div class="alert alert-${css} alert-dismissible" role="alert">
<button type="button" class="close" data-dismiss="alert" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
<strong>${msg}</strong>
</div>
</c:if>
<h1>All Users</h1>
<table class="table table-striped">
<thead>
<tr>
<th>#ID</th>
<th>Name</th>
<th>Email</th>
</tr>
</thead>
<c:forEach var="user" items="${users}">
<tr>
<td>
<!-- this do not work-->
<display:table name="user" export="true" id="row" >
<display:column sortable="true" title="ID" sortProperty="${user.id}" >
<c:out value="${user.id}"/>
</display:column>
</display:table>
${user.id}
</td>
<td>${user.name}</td>
<td>${user.email}</td>
<td>
<spring:url value="/users/${user.id}" var="userUrl" />
<spring:url value="/users/${user.id}/delete" var="deleteUrl" />
<spring:url value="/users/${user.id}/update" var="updateUrl" />
<button class="btn btn-info" onclick="location.href='${userUrl}'">Details</button>
<button class="btn btn-primary" onclick="location.href='${updateUrl}'">Update</button>
<button class="btn btn-danger" onclick="this.disabled=true;post('${deleteUrl}')" data-toggle="tooltip" title="${user.name}">Delete</button>
<button type="button" class="btn btn-warning" data-toggle="modal" data-target="#${user.name}" title="${user.name}">delete-test-button</button>
<!-- Modal delete Button-->
<div class="modal fade" id="${user.name}" role="dialog">
<div class="modal-dialog">
<!-- Modal content-->
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal">×</button>
<h4 class="modal-title">Modal Header</h4>
</div>
<div class="modal-body">
<p>delete User ${user.name} ?</p>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default" data-dismiss="modal" onclick="this.disabled=true;post('${deleteUrl}')"
data-toggle="tooltip" title="${user.name}" data-placement="left">OK</button>
<button type="button" class="btn btn-default" data-dismiss="modal">cancel</button>
</div>
</div>
</div>
</div>
</td>
</tr>
</c:forEach>
</table>
</div>