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I'm having trouble using the Spot effect in the Lighting category. The lens flare effect works great- I can set the HUD and then create a lens flare. But with the Lighting effects, I can set the HUD, but can't see any lighting in the preview, or after applying. Basically, I can see the HUD, but no lighting - what am I missing?

you need a layer with something on it to apply the lightning too.
do you have that?

nb : The layer must not be empty to use the lightning effect, or you won't see anything.