Material science can be like that … you’re pretty sure your theory works and your results don’t wildly invalidate it, but they aren’t good enough or are missing a property or something… and it turns out you could very easily have made a bad batch, poorly aligned fibers, badly mixed epoxy, or any number of possible issues… so you try again and again to get it right… sometimes it’s for very little incremental progress in state of the art… other times it might be a Nobel prize winning superconductor.