Here are a couple of clues:
Is your idea original? As a contest judge, I get to see thousands of stories a year. Many of them are roughly the same story told over and over again. For example, I get stories about “brain transfers” a lot. It might be a Freaky Friday kind of story, where two people switch bodies, or it might be a person getting his memories downloaded into a machine, or it might be a person getting his memories downloaded into a younger version of himself. The question is, do you have a unique take on this idea? Have you considered the idea more deeply than others?
If your idea is not original, if you’ve seen it time and time again, then your story might be weak at its very core, and perhaps you should look for a more-original idea.