PPA efforts only create an empty build directory with pbuilder or ppa itself

• Probably you are using a custom build location, so debian helper couldn't figure out automatically where are the files.

• DEBIAN?!!! in capital that mean this is a binary Debian package, Are you sure this is pre-built binary. Otherwise rename it to debian or recheck documentation.

• If you don't want changing build rules for files location. Write a debian/<packagename>.install file which map each folder or file (in build tree) to the correct location for installation. For example, if you want to copy the source-package/opt to /opt after installation, the contents of this file should be

  opt/* opt
  

Ref: Debian Maintainer Guide