Bug in "Integrating DHCP with DNS"?

I've been reading articles like this one:

http://technet.microsoft.com/en-us/library/cc771732.aspx

and all those "blah, blah, blah"

And this is what I put in the DNS tab (in all relevant places):

But I'm still unable to have non-Windows DHCP client's hostname registered in DNS.  Then I've found in a lot of other forums where people have encountered similar problems and never found solutions.

So, is there a bug in this so-called "Integrating DHCP with DNS"?

I'm using DHCP server inside a Windows 2008 domain controller (which also has DNS server) and another DNS server inside a Windows 2008 R2 domain controller.