Fixed a bug with the select group menu

~dev_rating/media/js/admin/students/index.js

@@ -48,6 +48,7 @@ $(function()
     $('#gradeSelect').change(function(){
         getStudentsList();
         $('#studyGroupSelect').attr('disabled', 'disabled');
+        $("#groupSelect").empty();
         $("#studyGroupSelect").html('<option value="0">--- Учебная группа ---</option>');
 
         if (($('#gradeSelect option:selected').val()!= '0')) {