How to display the new node added to the mother node...?

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JavaSE

how will I display the new node added to the mother node in a JTree object...?
My code displays the first child node created but not the second or the third and so on how will I display the other child nodes created...? Please help...

What I have tried:

String strRep=null;
       strRep=getID(); // this function returns null or a string value
       protected static DefaultTreeModel treeModel;// declared in class level
       boolean shouldBeVisible=true;
       if(strRep!=null) 
       {
        
	       String path=System.getProperty("user.dir");
        // getRepositoryName returns a string     
	    
		File Cr=new File(path + "/" + getRepositoryName() );
        	b=Cr.mkdir();
		DefaultMutableTreeNode nrep=new DefaultMutableTreeNode(getRepositoryName());
		 
	         if(b)
            	{
               		toolkit.beep();
		            treeModel.insertNodeInto(nrep, rep, rep.getChildCount());
		         }
       }
if(shouldBeVisible)
        {
            tree.scrollPathToVisible(new TreePath(nrep.getPath()));
        }