Nao capturar o campo na displaytag!

Front-end
#1 
      A jsp esta exibindo os campos normal sem dar nenhum erro !!!

 <html-el:form  action="/ExibirGerenciarVagas.do" method="post">
               
       
          <display:table name="colecao" pagesize="5" requestURI="/SAP/ExibirGerenciarVagas.do" id="colecao" cellspacing="20" cellpadding="8">
                     <display:column  title=""> 
                              <input type="radio" name="codCargo" value=" <c:out value="${colecao.codCargo}"/> " >
    		     </display:column>
                     <display:column  property="codCargo" title="Codigo do Cargo" />
                     <display:column property="desCargo"  title=" Nome do Cargo "/>
                     <display:column property="qtdVagas"  title=" Qtd. Vagas "/>
                    <display:setProperty name="paging.banner.placement" value="bottom" />
          </display:table>

  <hr color="#000000" size="5">
  <html-el:link href="/SAP/ExibirInclusaoVagaConcurso.do"> Incluir Nova Vaga  </html-el:link>  
  <html-el:link href="javascript:BotaoDetalhar(this);"> Alterar  </html-el:link> 
 </html-el:form>

Minha acao ta capturando o valor do campo codCargo que esta sendo exibido na displaytag

O problema é que ele esta sendo exibindo toda vez o campo nullo

public ActionForward execute(ActionMapping mapping, ActionForm form , HttpServletRequest request, HttpServletResponse response) throws Exception {
		
		    
		    FormularioGerenciarVagas fGerenciarVaga = (FormularioGerenciarVagas) form ;
            
            
	
		    System.out.println(fGerenciarVaga.getCod_cargo());
		    System.out.println(String.valueOf(request.getParameter("codCargo")));
		    System.out.println(String.valueOf(request.getAttribute("qtdVagas")));


			
	
	            return mapping.findForward("AlterarVagaConcurso");
	
}//fim do execute
#2