Problem with a collapsible class in jqmobile

Problem with a collapsible class in jqmobile

Hi i dont understand why is not working my collapsible role...  the code is:

the fragment of the html:
  2.   <div data-role="collapsible"><h3>Standard equipment</h3>
  3. <div id="div_equipamiento_standard">
  5. <!-- Here is the elements charged from .js-->
  6. </div>
The fragment of .js
  2.  var eq_standard = '';
  3. $.each(objVehicle.equimapiento_standard, function (i, item){
  4. //Titulo de la seccion
  5. eq_standard = eq_standard+'<div data-role="collapsible"><h3>'+i+'</h3><div class="texto"><span id="equipamiento_span">';
  6. $.each(item, function(i, item){
  7. eq_standard = eq_standard+ ' - ' + item + '<br />'  
  8. });
  9. eq_standard = eq_standard +'</span></div></div>';
  10. });
  11.  
  12. alert(eq_standard);
  13.  
  14.  
  15. $('#div_equipamiento_standard').html(eq_standard);
  16. });
The problem is in the .js... on eq_standard = eq_standard+'<div data-role="collapsible"><h3>'+i+'</h3><div class="texto"><span id="equipamiento_span">'; but i dont uderstand why the html dont charge the collapsible, but the <h3> charges correctly.
Thanks all and i hope you can understand the problem my english is a little bit bad.