Some stories don't work on the first attempt to write them, or the second, or the fifth, or the twentieth. I've had stories that came out in one draft, with only minor polishing required. More often, they come out in fits and starts, take a few dozen revision passes, and are settled and done.
Other stories take much longer. They yield failed draft after failed draft, false start after false start. When they finally come out right, they grow from old stories, or beginnings, or characters, that originated years (even decades) earlier. Apparently there's a certain amount of living I need to do before I know where to take them, how to end them.The book I wrote in 2012 was a relief in that it completed a story I'd been trying to tell for years. I'm happy now with that story. The way it turned out was much better than the way I originally conceived it; it needed that time and those changes in me to ripen.
I have another such a story still in me, a story I've been trying to tell in various formats, with various characters and plot twists, for longer than I care to remember. I produced a version several months ago that I had high hopes for, and received some feedback on it, and what I've since concluded is that I'm still stuck. That version has good things in it, but I still haven't found the right way to tell that story.
Maybe I never will, but as long as I'm around, I'll keep trying. Maybe it needs some life experience or inspirational spark that I haven't had yet. It might need some puzzle piece to fall into place. In the meantime, I've gone on to other things, but I can feel it in the background, biding its time.