Why in compositing the glare node with the streaks doesn’t work in cycles??? even if i have the correct light there is no way it works, is like if is not recognized the effect, i let the mix amount at maximum and i see only the black and i dont see the little stars.
Why is not working¡?¡? :’( , i was lot of time and nothing… create new files, change materials , lights, world settings … nothing happens…
You could always import the Render Cycles image back in to composite the Glare, but you probably know that 
you need to set the threshold on the node to a value less than 1.
It still doesn’t work im experiencing the same problem i think it has something to do with the fact that it renders the gray sky in cycles render layers. try changing the sky to just a transparent image.
**edit
if you go under world settings and switch to use nodes and pick transparent for the world background colour it works