I'm getting the following error when I try to update the value of a progress bar:

Error: $.widget.prototype._setData is undefined

Here is some test code that generated the error:

 

 <link type="text/css" href="ui.all.css" rel="stylesheet" />
 <script type="text/javascript" src="ui.core.js"></script> 
 <script type="text/javascript" src="ui.tabs.js"></script>
 <script type="text/javascript" src="ui.dialog.js"></script>

 <script type="text/javascript" src="ui.progressbar.js"></script>
 <script type="text/javascript" src="ui.datepicker.js"></script>

 <script type="text/javascript" src="effects.core.js"></script>
 <script type="text/javascript" src="effects.slide.js"></script>
 <script type="text/javascript" src="effects.fold.js"></script>
 <script type="text/javascript" src="jquery.ui.widget.js"></script>

 

function update_progressbar() {
   $("#progressbar").progressbar({value: 1});
   var curr_progress=1;
   
   while (curr_progress < 100) {
   curr_progress++;
    $("#progressbar").progressbar("option", "value", curr_progress );
   }

}