Google "link:" command errors = Penalty?

The Google LINK: command doesn't display results for my site anymore.

[myronlo]

I have a question for anyone who might know the answer. My website is over 6 years old. Previously, it has had a PR of 6 and has shown upwards of 1000+ backlinks using Google's link: command. On Yahoo, there are several thousand backlinks showing thus far.

In the past 3-6 months, everytime I use the link:www.my-site.com command in Google, I receive the error "Your search - link:www.my-site.com - did not match any documents."

Google still has most of my web pages indexed (as evidenced by using the site: command). Furthermore, my website still ranks organically for several keywords.

My question is this - is this error message using the link: command a Google bug? Or is this some type of penalty that has been imposed on my website? Again, up until a few months ago, this command was working just fine.

Thanks in advance.