Adsense doesn't show up properly

Hi there,

my website is www.chinasundae.com.

I have placed two google adsense ads in my rightside bar. My problem is those ads display very unstably. Both of them show up in the home page, one of them sometimes disappears when you open a posts.

This time, both ads don't show up on this post I just posted:
http://chinasundae.com/2009/12/06/10...-you-to-china/

Could someone please take a look and let me know why is that? Is there a way to fix or to avoid it from happening?

Thank you!

FangFang