Mac package installer installs the folder "Contents" in /Applications instead of the bundle

When I try to use packaging with my .app to create a Mac installer, and I run the installer, it creates me a folder named "Contents" in my /Applications folder, instead the "bundle app" as it should.

I've test with pkgbuild + productbuild:

pkgbuild --component "./myapp.app" --version 1 --install-location /Applications component.pkg
productbuild  --package-path "component.pkg" --distribution "./Distribution.xml" --package-path "./Temp" --resources "./Resources" --sign mycert "myapp.pkg"

And just with productbuild:

productbuild --component "./myapp.app" /Applications -s mycert myapp.pkg

In both cases, I run the installer, everything seems fine, but in Applications folder I see "Contents" (that is the content of the app bundle)

I've tried with "./myapp.app/" also in --component attribute, and even adding "/Applications/myapp.app" in the --install-location