Displacement shading error with mix material

[RahiSan]

Hey,

i get this wierd error when i try to plug a displacement into my skin shader.

This is how it looks without the displacement:

Basically i have 3 materials, two of them are mixed and the mix node is then mixed with the 3rd material. The displacement plugs into the latter mix node. The error seems to appear on 2 uv islands but not on the others.

Any tips how i could solve this?

THanks