Not working for me

I am using Drupal 6 and would like to change the order of the included javascript files. I am trying to use jslater.module to accomplish this.

However, when I implement hook_js_alter(), it seems to be having no effect at all on the included javascript files. Here for example is a test hook to set the querystring:

function mymodule_js_alter(&$js, $scope, &$querystring){
  dsm ("inside mymodule_js_alter");
  $querystring='123';
}

The hook gets called. But the querystring does not get set. Similarly, if I try to make changes to $js, the changes do not take.

Any idea what might be wrong?
Might these enabled modules be interfering with jsalter:
jquery_update
jquery_ui.