After completing my silicin re-seal I've found a light but noticeable scratch on a section of wall tile. Its light, as in my finger nail doesnt feel it


when scratched, but I wanted to see how I could seal it. Ive used clear and white wet area Selleys and nothing seems to fill it/stick to it.
What am I missing, or am I waisting my time? Scartch seems to go behind the silicon in the joint.