NodePreview =/= 3D Preview?

Delving into the Depths of Shaderforge I've come across an issue which may be a bug or just goes beyond my understandings.

I am working on Shader that should dynamically change it's visibility via 2 parameters (Thickness and Dottiness).
The desired result can be seen in the upper right corner, the preview image of the Multiply-node.

Picture 1: Thickness 0 Dottiness 0


Picture 2: Thickness 0 Dottiness 0.X


Picture 3: Thickness 0.X Dottiness 0



So both parameters seem to work separately.

What happens, when I combine both of them can be seen in

Picture 4: Thickness 0.X Dottiness 0.X




But the preview Image of the Multiply-Node in the upper right corner seems to be exactly what I am looking for. The Preview on the mesh on the left corner is pretty different though...
Shouldn't it be displaying what's being previewed in the upper right corner node?





I don't get this ^^ Could be a bug or maybe a bug in my brain? haha.

greets

Jules