Node Group Input showing as a Value instead of a Color

The inputs of my node group are represented as grey dots and have value sliders
instead of being represented as yellow dots and having an RGB box.

I have the inputs routed to Color nodes. Why isn’t it displaying correctly?


To be specific I am following this tutorial.
Notice the screen shot on the right of the page with the Group titled “Add6” and how it has Color Inputs.

You may receive more help if you can post a .blend file (even a stripped down version).

This can happen if when doing the adding and multiplying of nodes you use “Converter > Math”, instead of “Color > Mix (then changing Mix to add or multiply)”. Use "Color > Mix(add/multiply).