Endpoint Protection 12.1 not installing on Mac OS X 10.6

When I run the installer, I get:

Symantec Endpoint Protection can't be installed on this computer.

An error occurred while running the InstallationCheck tool for "Symantec Endpoint Protection". Try running the tool again.

And that's it.  So... what do I do?

It's a MacBook with 10.6.8 and I just installed the latest Java update (Update 11, 1.6.0_37)