How to fix a property error reported by XDCTools?

David,
it seems that the package 'pktlib' doesn't have a module 'Settings', which usually means that the versions of two different products on your package path are not compatible. The first thing you would like to find out is where is that package found. If you are already familiar with that package, you might already know which product brings it in, and then you can check in the product's documentation which version of SYS/BIOS is supposed to work with it.
A more generic solution for finding the location of a package is to use trace support in XDCtools and find a trace message that will tell you exactly where was the package loaded from. There are various examples on the linked Web page, but I think in your case it would be enough to define the environment variable XDC_TRACE_ENABLE to "load". I can't tell in which environment you are building, but if you are in CCS, there is also a way to define environment variables. Go to Project Properties->CCS Build->Environment.