apply class selector to click event can't work, why?

apply class selector to click event can't work, why?


HTML:
<DIV id='xAA'>
    <INPUT type='button' class='buttonOK' value='OK'>
    <INPUT type='button' class='buttonCancel' value='Cancel'>
</DIV>
 
javascript code:
 
$(document).ready(function(){
    ...
    $('#xAA > .buttonOK').click(function(){
            //do something
   });
});
 
Is there someone can help me? Thank's very much.