I build my form but the expression language not change it always returns null.

                    Bean (JobForm) :

                            final ExpressionFactory expressionFactory = FacesContext.getCurrentInstance().getApplication().getExpressionFactory();

                            final ELContext elContext = FacesContext.getCurrentInstance().getELContext();

                            FacesContext fc = FacesContext.getCurrentInstance();

                            Application application = fc.getApplication();

                             panel=new HtmlPanelGrid();

                              .....

                              .....

                              .....

                        final String expression = "#{jobForm.fieldDef['1']}";

                        final HtmlInputText input= (HtmlInputText) application.createComponent(HtmlInputText.COMPONENT_TYPE);

                        input.setValueExpression("value", expressionFactory.createValueExpression(elContext, expression, String.class));                   

                        panel.getChildren().add(input);

                    form.xhtml:

                         <h:panelGrid id="section_01" binding="#{jobForm.panel}" style="width:100%; border:0px;" columns="1" >

                         </h:panelGrid>

thank you for your help