The catch in Leibniz's Law

Eversince I read Kripke I can't get rid of that feeling that there is huge problem lurking in the LL. It is a numerical problem and it comes from language and not the world as it is. I could hardly be accused of being Millean about mathematics but I am pretty sure that even if some part of Frege's criticism is right the whole aproach was wrong. I mean, wrong. For as far as genuine metaphysics is involved properties might not happen to be just properties of concepts and thus a second order properties. I like the idea that our mind attributes numbers as properties to our concepts but I have the feeling that this does not help us much with the actual role maths plays in natural sciences. So yesterday I wrote 3k words on Kripke, blaming him for Lebniz's faults. I mean, the guy is still alive and can do somethign about it. Leibniz can't, Frege too so it would be a kind of unfair :).