oops - I believe I found the problem, it's between the keyboard and the chair.
I created a package that would install to D:\Program Files\ ... but tested it on a machine with a different disk configuration, C: only, no D: at all.
jftr, the msi log was actually in %USERPROFILE%\AppData\Local\Temp and gave the following message...
Error 1324. The path Program Files or the volume is invalid. Please enter it again.
Thx for the heads-up that this log existed!
