title: systemd apparently not finding .service file
body: <p>I've put together a foo.service file for our foo service that runs as a daemon.  The service runs fine when I run <code>systemctl start foo</code> (and <code>stop</code>) but 
  <code>systemtcl enable foo</code> results in <code>Failed to issue method call: Invalid argument</code>.  The unit file is placed in <code>/etc/systemd/system/foo.service</code>, and has permissions 0755.  Setting systemd to debug and running enable gives </p>
  
  <pre><code>Looking for unit files in (highest priority first):`
      /etc/systemd/system
      /run/systemd/system
      /usr/local/lib/systemd/system
      /usr/lib/systemd/system
  Looking for SysV init scripts in:
      /etc/rc.d/init.d
  Looking for SysV rcN.d links in:
      /etc/rd.c
  Failed to issue method call: Invalid argument
  </code></pre>
  
  <p>Googling around, it <em>seems</em> like systemctl isn't finding the .service file.  Is there any way to verify that?  If so, how can I fix that?  Any other ideas about what might be wrong?  Is there more debugging I can enable?  The debug info given doesn't really help me narrow down the problem.</p>
  
  <p>foo.service looks like:</p>
  
  <pre><code>[Unit]
  Description=Blah Blah Blah
  
  [Service]
  ExecStart=/usr/bar/doof/foo
  Type=simple
  PIDFile=/var/run/foo.pid
  
  [Install]
  WantedBy=multi-user.target,graphical.target
  </code></pre>
  
  <p>EDIT: Yes, I did run <code>systemctl daemon-reload</code>.  </p>