Is the Grass Tool working properly

Hi
I have just finished the ‘Grass Tool Quick Start’ Guide an official guide form unreal’s docs.unrealengine.com but every time I create the Grass Material exactly as in the guide, when I click on “Apply” I get a dialog box appear telling me

  • Warning: Compilation errors in this Material. - The current material has compilation errors, so it will not render correctly in feature level SM5. Are you sure you want to continue.

If I do click Continue the Display Sphere in the top left of Unreal Engine turns Black…My Material is set up exactly as the image is in the Guide. I have just updated to UE4.23 and exactly the same thing happens. Is this a bug or is the Grass Tool an old out of date function in Unreal Engine and Level Designers use more up-to-date, possible 3rd party tools to create grass in their scenes. Many thanks to anyone who would be able to help on this