Cannot build rpm from tarballs (x86_64)

Hello *,

I bought a brandnew TARGA DataBox NDAS 400 drive with ethernet and USB connector. In order to get it run under my openSuse 10.2 on my AMD x86_64 machine I downloaded the x86_64 drivers offered under
http://code.ximeta.com/trac-ndas/wiki

Then I tried the instructions to generate a working version out of the
ndas-1.0.5-19.x86_64.tar.gz

as described on http://code.ximeta.com/trac-ndas/wiki/HowToBuildRPM

so I opened a shell and did a su....
and then tried:

2. Build the ndas rpm

rpmbuild -tb ndas-1.0.2-24.tar.gz --target=`uname -m`

and you will get the RPM file under

/usr/src/redhat/RPMS/i386/ # Redhat / Fedora
/usr/src/packages/RPMS/i386/ # SuSE (or /usr/src/packages/RPMS/<output of "uname -m">)
/usr/src/RPMS/RPMS/i386/ # Mandriva

But already the first command "rpmbuild" dropped an error:

#rpmbuild -tb ndas-1.0.5-19.x86_64.tar.gz --target=`uname -m`
Building target platforms: x86_64
Building for target x86_64
error: Architecture is not included: x86_64
#

Can anyone help?