Strumpy shader - Overlay(Add) two textures for Unlit

Hey guys I'm having a small problem making a custom sky-dome shader.I'm following this tutorial for UnrealEditor -

Animated Skydome in UnrealEditor

So now I'm using two textures,a sky diffuse and cloud mask.I want to overlay (or add or whatever) the cloud mask texture over my sky-dome diffuse texture and animate it afterwards.I tried in Unreal Editor and its working fine but when I tried the logic in Strumpy Shader Editor its adding the color values instead of overlaying and gives more brightness.

I'm posting my shader graphs and results from both Unity(Strumpy Editor) and Unreal Editor

Unreal Editor Graph and Result

Strumpy Editor Graph and Resul