emissive color applied shadows of normal map

I’ve created a Earth shader which shall show the city lights on the unlit part of the Earth. I’ve masked the textures accordingly. However when using a normal map the emissive color is shown on normal map shadows even when masking. I’ve attached these two pictures. For a better visualization I’m simply using a red color.

Answer from Arnage UE4 Forum

This is the expected behaviour as you are using the pixel normal (PixelNormalWS node). To get the effect you intended you should use original vertex normal instead (VertexNormalWS node).