Django admin's filter_horizontal (& filter_vertical) not working

I'm trying to use ModelAdmin.filter_horizontal and ModelAdmin.filter_vertical for ManyToMany field instead of select multiple box but all I get is:

My model:

class Title(models.Model):
    #...
    production_companies = models.ManyToManyField(Company, verbose_name="компании-производители")
    #...

My admin:

class TitleAdmin(admin.ModelAdmin):
    prepopulated_fields = {"slug": ("original_name",)}
    filter_horizontal = ("production_companies",)
    radio_fields = {"state": admin.HORIZONTAL}
    #...

The javascripts are loading OK, I really don't get what happens. Django 1.1.1 stable.