Sorry, I assumed you were using C# because of the unfamiliar code I saw as the second parameter of your call to LoadAssetPath().
When I use LoadAssetAtPath() I use it like this:
var newMat = AssetDatabase.LoadAssetAtPath("Assets/blue.mat", Material);
I’m not sure if that’s the problem or not. I would give it a try both ways. I don’t have a machine with Unity handy, but I’m curious to see the output of: