controllo JS su campi ajax (nascosti) di un form

[-AA-]

Si bene
funziona

<form name="test" action="tedt" method="post">

<select name="prima" onChange="controlla(this.value)">
<option name="zero" value="">zero</option>
<option name="uno" value="1">uno</option>
<option name="due" value="2">due</option>
<option name="tre" value="3">tre</option>
</select>

<input type="text" name="aaa" id="altrocampo" style="display:none"> 


<input type="submit" name="submit" value="send" />
</form>
		<script language="JavaScript" type="text/javascript"
		xml:space="preserve">//<![CDATA[
		var frmvalidator  = new Validator("test");
		frmvalidator.addValidation("prima","req","Selezionare");
		
function controlla(valuta) { 
if(valuta <= 1) { 
document.getElementById('altrocampo').style.display='none';
}else{ 
document.getElementById('altrocampo').style.display='';
		frmvalidator.addValidation("aaa","req","compila anche il campo aaa");

} 
}
		
		
		//]]></script>