Java Refresh info

Hi I've do this code, in ADD Page IF value = 5 then I can see the field named patenti else not. But if I select 5 and after I change it, the field patenti doesn't disapper from page. <img src='https://asprunner.com/forums/file.php?topicimage=1&fieldname=question&id=19147&image=1&table=forumtopics' class='bbc_emoticon' alt=':angry:' />
var TS = Runner.getControl(pageid, 'tipo_documento');

var IDF = Runner.getControl(pageid, 'patenti');

TS.addCSS('highlight');

//setto tutti i campi off

IDF.hide(); //patenti
TS.on('change', function(e){

if (this.getValue() == '5')

{

IDF.show(); //mostra patenti

}

});
TS.on('change', function(e){

if (this.getValue() != '5')

{

IDF.hide(); //mostra patenti

}

});