First of all, the 17-40 4L isn't the best lens for IR on the 20D. If you searched the forum you'd have seen many 10D users reporting they had better success with the 50 1.8...though then you lack the wide angle. The other mistake you made was shooting at ISO 400. You never take these types of photos at ISO 400. Try it again at ISO 800 or 1600, on a different lens and try shooting at f3.2 or something like that. You'll get far better results.