Google language recognition problem ?

Hi guys,

I have a page in German. Only in German, all the possible meta tags are showing that the site's language is German.

If i do a search for the keyword the page was optimized for on google.com then it appears around the 5-15 place. If i go to "advanced search" and switch on German then it disappears.
On google.de it does not appear at all. In fact it appears in every native google page except for google.de.
It seems like google is blocking the page but only for a specific language. The site's native language. But i've never ever heard of a language specific penalty.

Also on google.com for the keyword all the German results have the "Translate this page de->en" link next to them. Except for my page ! Does it think that my page is in English ?

Is it possible that google failed to recognize the page's main language ? There is enough text there, it must be getting useful statistics.

I'm just baffled, has anyone ever seen something like this ? Customers obviously getting google.de as their default page