Color Change by High Range Modifier

Hi guys, I want to print a certain layer in a different color. I load several parts to one object and then I want to use the High Range Modefier. But somehow it does not work anymore. However, it worked before. Of course I know that I can also use the paint function to color the layers, but that is not 100% accurate. Maybe someone knows something about this .

Greetings and happy Printing