Sidebar disappear on specific post address

Dear all,
Here is my problem:
My sidebar appears when I use this address:
https://thechinagateway.com
or
https://thechinagateway.com/category/doing-business/
But the sidebar does not appear when I use this address:
https://thechinagateway.com/2012/05/21/watch-sales-statistics-in-china-1/
or
https://thechinagateway.com/2012/05/02/the-country-where-trains-leave-early/

Does anyone has any idea how I can make it appear on every page and post?

Config:
Twenty Eleven 1.3
WP version 3.3.1
Crome
Plugins:
Google Analytics for WordPress
FeedBurner FeedSmith
Quick Page/Post Redirect DEV (used to redirect a page on a category – see heather menu)
Subscribe2
Under Construction

Thank for your help !