Hi,
I'm trying to create an expression to make my instanced objects (simple disc shapes) rotate randomly as they fall. I have added a general PP attribute, but when I try this expression:

particleShape1.rotPP = rand (0,360);

I get an error saying :

Warning: Expression Editor: no particle object is selected.

This means that I can't go on to connect the rotation expression to the rotation of the disc shapes.

Any clues on what I have done wrong?

(I am following a falling leaves tutorial, but simply changed there instanced geometry to mine for a project I am working on).

Any help very much welcome, Cheers in advance.

Chris