In the Niagara Quickstart
https://docs.unrealengine.com/en-US/…art/index.html
Step 8: Drag off the RGB output of the Texture Sample node, and plug it into the Gradient input of the Value Step node.
Should be “Drag off the R output…”
Connecting RGB will give a compilation error. The image in step 9 shows the R channel correctly connected.