error fetching MTL-4

Hi there!
Do you know why https://simunova.zih.tu-dresden.de/mtl4/dwtable is not secure?
Download of MTL-4.0.8368-Linux.tar.bz2 is rejected:
(with dorsal and dorsal-dev on Debian Squeeze)
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Fetching MTL-4.0.8368-Linux
--2011-08-12 14:43:02-- https://simunova.zih.tu-dresden.de/mtl4/dwtable/MTL-4.0.8368-Linux.tar.bz2
Tražim simunova.zih.tu-dresden.de... 141.30.75.9
Spajam se na simunova.zih.tu-dresden.de|141.30.75.9|:443... spojen.
UPOZORENJE: cannot verify simunova.zih.tu-dresden.de's certificate, issued by `/C=DE/O=Technische Universitaet Dresden/OU=ZIH/CN=TU Dresden CA - <email address hidden>':
  Unable to locally verify the issuer's authority.
HTTP zahtjev poslan, iščekujem odgovor... 404 Not Found
2011-08-12 14:43:03 GREŠKA 404: Not Found.

Failure with exit status: 8
Exit message: Error fetching MTL-4.0.8368-Linux.
"
Regards, Zeljka