jquery cannot hide span attribute in Drupal 7 What is wrong with this jQuery code and why can it not hide the span attribute?

jQuery(document).ready(function($){
    $('span.fieldset-legend').hide();
}); 


Heck, just trying to hide the entire span and it still does not work!

jQuery(document).ready(function($){
    $('span').hide();
});


If it helps, I am trying to hide a horizontal item in a horizontal group.


I can confirm that my jQuery is generally working.  For example, the below works fine

alert('test');


This also works fine

jQuery(document).ready(function($){
    $('p').hide();
});
Just a wild guess but

jQuery(document).ready(function($){
  $('span.fieldset-legend').hide();
  console.log('Hidden the spans');
}); 


Try the above code and see if "Hidden the spans" gets output on your javascript console. If it does, then the module you're using (Horizontal Groups? or whatever) is tampering with the spans and perhaps showing them after your code has run and hidden them.