VTD-XML in Java - Sequential usage of several `insertAfterHead` doesn't work

Question

I need to paste int XML file several elements in one time, so I have the code:

public void writeElement(String parent, String element, String content) {
    try {
        xmlModifier = new XMLModifier();
        xmlModifier.bind(vtdNav);
        vtdNav.toElement(VTDNav.FIRST_CHILD, parent);
        xmlModifier.insertAfterHead("<" + element + ">" + content + "</" + element + ">");
        xmlModifier.output(filepath);
        xmlModifier.remove();
    } catch (ModifyException | NavException | IOException e) {
        e.printStackTrace();  
    }
}

I call this method several times sequentially:

dbFile.writeElement("patient", "surname", surname);
dbFile.writeElement("patient", "name", name);
dbFile.writeElement("patient", "patronymic", patronymic);

But the result is:

<db>
   <patient>
      <patronymic></patronymic>
   </patient>
</db>

Why only the last calling of method is executing? And how to change the code to fix the problem?