The best thing to do i think would be to listen to the track with all your concentration..."go deep"...close your eyes if you have to. And listen to it until your ears start to hear the missing element. I say this b/c there have been tracks where i can hear exactly what element i need to add in order to enhance the sound. If that does not work try experimenting with sounds. Also listen to the entire sample for some suggestions on additional sounds to add to your track....and then try to find that sound and manipulate it the way you want to. Try stuff out there are many routes that you can take in order to find the missing element.

Good Luck