"True" and "False" do not work, to disable, set to value disabled.
$('.someElement').attr('disabled', 'disabled');
To enable, remove.
$('.someElement').removeAttr('disabled');
Also, don't worry about multiple items being selected, jQuery will operate on all of them that match. If you need just one you can use many things :first, :last, nth, etc.
You are using name and not id as other mention -- remember, if you use id valid xhtml requires the ids be unique.