This is what I've done:

My samples are wood meal in sodium acetate buffer. My standard curve is glucose dissolved in water and then diluted with sodium acetate buffer. My blank is just sodium acetate buffer. I added freshly prepared DNS solution (according to Miller 1959) and incubated in 100 degrees for 15 min. What I see after incubation is that the blank had no colour change, but the standard curve was backwards - the one with the highest concentration was the lightest and the one with the lowest concentration was the darkest. I did everything in triplicates except the blank and the replicates all looked the same. My highest concentration of glucose was 1g in 1 ml of water and this was much darker than the samples I have. Since the standard curve was backwards, that would mean that I had enormously high levels of reducing sugars in my sample - much more than the amount of wood meal I added. What on earth did I do wrong? (Yes, the measurements from the spectrophotometer are in accordance with the visual results)