How was the package added to the JSS?
Did you by any chance add the package manually to your distribution point or copy a new version of the package to it and then change the package name or information in the JSS web interface or just copy a new version over the old one and did nothing else?
Asking because when you use casper admin to upload a package to the distribution point, it writes a checksum to the database and if the package doesn't match that checksum it will fail to install.
Our primary distribution point is on BOX so we can't use Casper Admin to upload packages so we have to manually upload them and then create the package object in the JSS via the web interface. We had to turn off checksum checking in the JSS because of this.
