what version of debian are you using, and what is the package you're building?
I've had success building debian packages using the debian/rules file. You find it in the (any) debian source package under the debian directory. It's like a Makefile, and you can edit it (if you feel up to it) and then, from the root of the package's directory tree you type something like...
Code:
fakeroot debian/rules binary
This builds the deb package and places it in the parent directory. The really crucial thing is that you can set all the variables you want in the 'rules' file.
On the other hand maybe the package you're trying to build can be found on debian-multimedia or backports.
EDIT: sections in this doc talk about downloading source packages using apt-get... see section 7.14 where they even mention the debuild command you used.
http://www.debian.org/doc/FAQ/ch-pkg_basics.en.html
Also I was hasty to say that 'any' debian source directory had a debian/rules file.