Compiling 64bit from 32 bit (xojo example)

Using a Windows 7 32 bit I can compile my applications for 64bit with no problem.
But I tried to do the same with Xojo example: C:\Program Files\Xojo\Xojo 2016r1.1\Example Projects\Graphics and Multimedia\FluidsDemo.xojo_binary_project, and I can’t.

When I click x86 64-bit at the inspector panel “Build|Architecture” nothing happens. Run green arrow is still operative and if I Build what I get is a 32bit application.

Is it something special with this application?