behind 2011 banner

I can’t find a way to get the snow to fall over the top of the banner using a 2011 child theme – I tested the default twenty eleven theme and the snow goes behind in that too, so it is not a problem with the child theme. I can see the z-index is set to 1000 so really it should be falling in the front. Any idea how to get it to work? Thanks and merry christmas, ho ho ho…

http://ww.wp.xz.cn/extend/plugins/nksnow/