error status is not updated after value is set by js

[cai123456jun]

for example:
html:
<input name="exam" type=text id=exam />
<input name="totalScore" type=text id=totalScore />
<input name="outstandingScore" type=text id=outstandingScore/>

JS:
$('#totalScore').change(function (evt) {
var score = parseInt($('#totalScore').val());
$('#outstandingScore').val(score * 0.9);
});

    var metrics = [
        [ '#exam', 'presence', 'cannot be empty' ],
        [ '#totalScore', 'presence', 'cannot be empty' ],
        [ '#outstandingScore', 'presence', 'cannot be empty' ]
    ];

so if someone types something in the #totalScore, #outstandingScore will be populated automatically inside change event. but after change event, error is still set on #outstandingScore

[cai123456jun]

my bad. needs to do : xxx.val(abc).change().