When you deploy a compiled 4D Server application on Mac OS X and try to connect from 4D Client, you might get an error that says: 'This database does not work on PC machines.'

Why does this happen? It happens because the application has not been compiled for both Mac OS and Windows.

The solution is to select the 'always compile for both platforms' checkbox in 4D Preferences. This checkbox can be found at: 4D Preferences -> Design Mode -> Compiler -> Always compile for both platforms

Recompile your application to see success!