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:
  1.   <div data-role="collapsible"><h3>Standard equipment</h3>
  2. <div id="div_equipamiento_standard">
  3. <!-- Here is the elements charged from .js-->
  4. </div>
The fragment of .js
  1.  var eq_standard = '';
  2. $.each(objVehicle.equimapiento_standard, function (i, item){
  3. //Titulo de la seccion
  4. eq_standard = eq_standard+'<div data-role="collapsible"><h3>'+i+'</h3><div class="texto"><span id="equipamiento_span">';
  5. $.each(item, function(i, item){
  6. eq_standard = eq_standard+ ' - ' + item + '<br />'  
  7. });
  8. eq_standard = eq_standard +'</span></div></div>';
  9. });
  10.  
  11. alert(eq_standard);
  12.  
  13.  
  14. $('#div_equipamiento_standard').html(eq_standard);
  15. });
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.