Codesign Error

[Colin Holgate]

Here are steps that someone doing a Unity app succeeded with, there may be something in the lines that stands out as being different to what you're doing:

Permissions - Change permissions of Unity's Data folder - it has to get read rights for "everyone" 
chmod -R a+xr "Bubble Bang.app/Contents/Data"

Code Signing:
codesign -f -s "3rd Party Mac Developer Application: Martin Schultz" "Bubble Bang.app"

Build package:
productbuild --component "Bubble Bang.app" /Applications --sign "3rd Party Mac Developer Installer: Martin Schultz" --product "Bubble Bang.app/Contents/Info.plist" BubbleBang.pkg

Testing:
sudo installer -store -pkg "BubbleBang.pkg" -target /