Problem with droppable and FF

Problem with droppable and FF

Hello, I am creating a droppable component and has a very rare problem with FF i don't know why doesn't append the clone of the component to the droppable widget, and just dissapear the widget. here it's the code, of the draggable function and the droppable function 

Draggable: 
  2. function makeDrag(elmnt){
  3. $(elmnt).draggable({
  4. helper:'clone',
  5. cancel: null,
  6. scroll: true, 
  7. scrollSensitivity: 100
  8. });
  9. }
Droppable:

  2. function actvDrop(widget){
  3. $(function() {
  4. $("#"+widget.getAttribute('id')).droppable({
  5.             drop: function(event,ui){
  6. if ($(ui.draggable).attr('new') == 'true')
  7. {
  8. clone = $(ui.draggable).clone();
  9. $(clone).mouseover(function(event){
  10. showprp(this);
  11. });
  12. $(clone).attr('new', 'false');
  13. var clnumb = parseInt($(clone).attr('clone'));
  14. var newIndex = (clnumb+1);
  15. $(ui.draggable).attr('clone', newIndex);
  16. $(clone).attr('id', ((newIndex)+$(clone).attr('id').substring(1)));
  17. $(clone).css({position:'absolute', top:event.pageY, left:event.pageX});
  18. $(this).append(clone);
  19. makeDrag(clone);
  20. }else{
  21. $(ui.draggable).css({position:'absolute', top:event.pageY, left:event.pageX});
  22. $(this).append(ui.draggable);
  23. }
  25.             }
  26. });
  27. });
  28. }
Sincerly i need your help i don't know what do now