That's normal of the PKG filter of ZModeler 1.07b, that always make the program to crash when importing most of the .pkg files, at least.
You must replace it with Maxoff's edited one, which works very well for importing. Download it
here, open the archive with WinRar or 7Zip, extract both the files from the archive to the Filters folder present in the ZModeler installation folder (usually it's in the directory C:\Program Files (x86)\ZModeler) replacing the existing ones, and finally run the program to try the new filter.