Sitemap Not Found

Hi,

a week ago I was told to re-verify my sitemap. I uploaded the
verification file but Google told me the file was not found. After 10
tries, Google accepted the file...

But since that, my sitemap is always indicated as "Not found". It's
definitely there, so I don't know why it doesn't work.

URL to my Sitemap: http://www.arnebrachhold.de/sitemap.xml

Non-existing sites are returning correct 404 headers and I see no 404s
in my logfile, so I can't understand why Google doesn't find it.

Checked:
-that your verification file exists in the correct location and is
named correctly (in your case, you've already check this)

-> Yes, it's there and i can access it from several computers

-that your webserver is up and responding to requests when we attempt
the verification

-> It worked after several tries

-that your robots.txt file doesn't block our access to the file

-> My robots.txt is empty

-that your server doesn't return a status of 200 in the header of 404
pages

-> Works. Sitemap is 200, 404 is 404.

What can I do?

Best regards,

Arne