hi Ella!
hmmmm. okay, the 1316 is fairly exotic ... i think you're the first one i've seen in an itunes context.
we have had success with these "undocumented errors" though.
first, throw away the current installers and download fresh ones from the website. here are the Installshield Tips and Pointers on installation best practices:
http://consumer.installshield.com/faq.asp#ts
apply these to your situation. (probably best to start off with the simpler ones and work up to the more aggressive measures.)
good luck! keep us posted on your progress.
... also, if you've got the time, would you mind reporting your error to InstallShield?
http://consumer.installshield.com/submit.asp
i'm not sure if they'll get back to you, but i guess if we keep reporting these "undocumented errors", we might get some more documentation on them sooner rather than later ...
love, b