Content Type Description is not adding on list

Hello

I have some custom content type on site level and each content type I have different description. When I add content type manually  in existing document library, description is also coming for added content type. But when I add content type programmatically, description not coming with content type it is coming as empty. I have used following MSDN article for adding content type.

http://msdn.microsoft.com/en-us/library/office/aa543576(v=office.14).aspx

Can one please let me know what am I missing here?

Regards

Avi