change category does outcome new class's manners being receptive ie6?

i have unparalleled settlement 9 opposite states suitable background-position manners set adult classes arrangement opposite states. i can't :hover pseudo-selector since credentials settlement being altered same component being hovered over. i have tangible classes way:

#chooser_nav {width:580px; height:38px; background:transparent url(/assets/images/chooser-tabs.jpg) 0 0 no-repeat; margin-left:34px;}
#chooser_nav.feat {background-position:0 0;}
#chooser_nav.inv {background-position:0 -114px;}
#chooser_nav.bts {background-position:0 -228px;}
#chooser_nav.featinv {background-position:0 -38px;}
#chooser_nav.featbts {background-position:0 -76px;}
#chooser_nav.invfeat {background-position:0 -152px;}
#chooser_nav.invbts {background-position:0 -190px;}
#chooser_nav.btsfeat {background-position:0 -266px;}
#chooser_nav.btsinv {background-position:0 -304px;}

then, controlling jquery, i have array float manners formed before click eventuality (the here-undeclared "cur" non-static morally announced elsewhere):

  $("#featured_races a").hover(function(){
    hybrid == "feat" ? $("#chooser_nav").attr("class", cur) : $("#chooser_nav").attr("class", cur+"feat");
  }, function(){
    $("#chooser_nav").attr("class", cur);
  });

  $("#invitational_races a").hover(function(){
    hybrid == "inv" ? $("#chooser_nav").attr("class", cur) : $("#chooser_nav").attr("class", cur+"inv");
  }, function(){
    $("#chooser_nav").attr("class", cur);
  });

  $("#behind_the_scenes a").hover(function(){
    hybrid == "bts" ? $("#chooser_nav").attr("class", cur) : $("#chooser_nav").attr("class", cur+"bts");
  }, function(){
    $("#chooser_nav").attr("class", cur);
  });

so, moz webkit browsers, works fine. classes receptive credentials settlement changes accordingly. works ie7 well. however, ie6, credentials settlement never changes. classes receptive appropriately, i accurate dom spectator ms's web dev tool. so, jquery working. category removing applied, nonetheless change visibly occurring.

i'm kinda stumped here... assistance me, impulse ... you're wholly hope...

edit:
as distant classname vs. setattribute... category changing. attr("class", cur) working. however, once category changed, indirect manners receptive visually... nonetheless change category occurring.

edit 2:
as jquery's class-specific methods: i creatively code, outcome same. again, problem category removing receptive element... accurate happening. it's once category element, reason, component following css manners set class...