Incompatible version trying to install 5.16.2 over 5.16.1?

I am trying to upgrade an ActivePerl installation and I keep getting the error message

"The selected directory contains an incompatible version of ActivePerl. Please choose a different installation location!"

I find this difficult to believe because I am trying to install 5.16.2 Build 1602 over 5.16.1. Build 1601 ... seriously, one minor revision cannot be upgraded?

I tried turning on verbose msi logging by invoking the install thusly:

msiexec /i ActivePerl-5.16.2.1602-MSWin32-x86-296513.msi /l*v ActivePerlInstallLog.txt

But there isn't anything (like perhaps an incompatible package?) that indicates why it thinks my version is an incompatible one that cannot be upgraded.

Anyone have any suggestions, solutions?

Thanks &
Cheers,

Toby