Error building multiple .pde files.

[Norsak]

The way I understand .pde files is:
They get concatenated in alphabetical order, then compiled. (not pre-compiled)
https://arduinodilettante.wordpress.com/2011/03/10/multiple-file-sketches/

I currently get an error from _ino build_
src/z_loop.pde: In function ‘void setup()’:
src/z_loop.pde:4:17: error: ‘setup_NeoPixel’ was not declared in this scope

I my scenario there are 2 files in the src/ folder:

a_NeoPixel.pde
z_loop.pde

The function _setup_NeoPixel()_ is declared in the file _a_NeoPixel.pde_
But when i try and call it in _z_loop.pde_ ino reports the above error.

The same code works in the Windows Arduino IDE (using 2 .pde files in the same folder, which show as 2 tabs in the IDE)

What do I need to do differently in ino to make this work?