wp_enqueue_script version problem

hi! I’ve wrote this (in a function called add_mootools in functions.php)

wp_enqueue_script('mootools','',array(),"1.2");

But the problem is that the html output has always the same version (the wp version!!! And this is strange too.. ), just as I didn’t pass it:

<script type='text/javascript' src='http://reghellin.unbit.it/test-nino/wp-content/themes/el-nino/js/mootools.js?ver=2.9.2'></script>