The glare node works based on a threshold value. Meaning only the pixels that have values larger than the set value will be affected by glare/bloom/glow.
Use a lower value until you get what you need.
Also, keep the mix at $0$. If you set it to $-1$ you are actually cancelling the effect completely.
Value to control how much of the effect is added on to the image. A value of -1 would give just the original image, $0$ gives a $50/50$ mix, and $1$ gives just the effect.
Pixels brighter than this value will be affected by the glare filter.
(Form the blender manual)