Cointainer-Rendering Problem, but with the addition...

I solved the problem, but instead the easier way in combination with 
"insert()", I've used "find()".

Depending on my selectedItem from the Combobox, I call up the function as 
following:
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           String xml_file = null;
           String command = new String();
           command =((JComboBox) e.getSource()).getSelectedItem().toString();
                     
         if (command.equals("Schule"))
            {
               xml_file = "schule.xml";
              // System.out.println(xml_file);
               showLabel(xml_file, Color.BLUE);
            }

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[snip]











public void showLabel(String _lab, Color _color)
    {
        String lab = _lab;
        Color color = _color;

     try{
                
               swix = new SwingEngine(this);
               swix.render( "xml/"+ lab ).setVisible(false);
               
               //Anzahl der Labels
               //System.out.println(swix.getIdMap().size()-1);
               
                //Container ungueltig setzen
                center_panel.invalidate();
                
                //Entfernen aller Componenten
                center_panel.removeAll();
          
               //Hinzufuegen der neuen Componenten zum center_panel
                for(int i=1; i<=swix.getIdMap().size()-1; i++)
                {              
                center_panel.add(swix.find("lab"+i));             
                swix.find("lab"+i).addMouseListener(mausi);                
                }
      
                
                
                center_panel.setBackground(color);
                //Container gueltig setzen
                center_panel.validate();
                
                
                //Componenten neu zeichnen
                center_panel.repaint();
                

            }
            catch(Exception y)
            {
                System.out.println("Fehler" +y.getMessage());
            }
}