@[email protected]

dpkg doesn’t resolve dependencies (that’s a feature of apt) which means that if you install a Debian package with dpkg, you’ll have to manually install all dependencies first, and they won’t be marked as automatically installed

Usually installing a manually downloaded package and its dependencies works like this:
# dpkg -i package-file.deb
# apt-get -f install

So apt-get can be used to install missing dependencies afterwards while marking them as automatically installed.