Page is a not externally linkable
-- Google SEO News and Discussion
---- "Links to your Site" in Google Webmaster Tools
ZydoSEO - 2:40 am on Jan 13, 2013 (gmt 0)Thread source:: http://www.webmasterworld.com/google/4535466.htm
I agree with Robert. Your linking site likely has canonicalization issues. Perhaps every page on your site can be referenced both with and without the www.
Brought to you by WebmasterWorld: http://www.webmasterworld.com