link:not showing top level page

why is the top level page linking in not showing?

[Namaste]

I have noticed that Google isn't displaying the top level page linking in. For example:
link:www.webmasterworld.com/forum96/

does not show www.webmasterworld.com or www.webmasterworld.com/index.htm as a page linking in. All kinds of other pages are registered.

Also, why is this particular page PR5 when the homepage is PR7?