If the challenge was about "Life Lines" or "Lines that lead to Life" or the "Power piping sytem of nature", you would have nailed that theme. I think where you made a mistake when you changed the theme a little to meet your entry. The Challenge is Leading Lines. What you should have shot was an image where your eye is being lead in a direction by the subject in the photo. There are so many lines in the leaf, it just looks like a puzzle.
Your leaf is very interesting, almost looking like there is a light behind it because of the yellowish tint to the viens. The colors seem to be oversaturated, maybe this was your intent. I would have sharpened the image some to bring out the detail.
Overall, this is a great example of texture with bright vivid colors. IMO, not a good choice for the theme, thus your low score. What I have noticed here at DPC is that your image for a challenge needs to hit the theme DEAD ON. If a viewer has to read the title to undertand the relationship to the theme, it is not going to get good votes. The theme should just jump out at you when you look at it. Keep trying and Good Luck in future challenges.
There are lines, yes. It is a very nice picture. I just don't feel it meets the challenge. Where are they leading? I don't find myself being led anywhere. There is no central focus.
whilst i think this image was well executed, i do think the subject is a bit on the trite side. perhaps i've just seen this one too many times. 6 for the nice execution.