Error while redirecting from one page to another, passing parameters

Hi. I have Page 20 in my Application, with a Button that executes the following:

Dynamic Action that calls the following 'Execute Javascript Code':

apex.server.process (

  "PROCESAR_DOCUM_AJAX",                

  {

    pageItems: '#P20_ID, #P20_INSTITUTION, #P20_DOCUM, #P20_FECHA, #P20_PROVIDER, #P20_CONCEPTO, #P20_SERVICENAME, #P20_TYPE, #P20_PAYMENT_TYPE, #P20_PAYMENT_REFERENCE, #P20_VALOR'

  },

  {

    dataType:"text",             

    async:false,               

    loadingIndicator:"#P20_CONCEPTO",   

    success:function(pData){         

    console.log('Success');

    $s('P20_ERRORES',pData)         

    }

  }

);

var patientID = $v('P20_ID'); //This value comes from the client not the session!

apex.navigation.redirect('f?p=&APP_ID.:21:&APP_SESSION.::NO::P21_ID:' + patientID);