rotation expression troubles
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.