Animation clears radio button's CHECKED attribute in IE

I have a <DIV> container which contains radio buttons. When I toggle/show/hide that container with options, the radio buttons are cleared in IE, but not in Firefox.

Example of what works:

$('#lp_del').click( function () {

$('#sp_ded').toggle( );

});

Example of what doesn't:

$('#lp_del').click( function () {

$('#sp_ded').toggle( "blind", { direction: "horizontal" }, 500 );

});

The <DIV> container sp_ded hides, but before it does, the CHECKED radio button is first unchecked. When container reappears, the radio button is still unchecked. However, in Firefox, the container remains checked all the way through.

Remember, the radio button is left alone if no options are given for toggle/show/hide, but unchecked when options are given.