How do we do Subsurface scattering? It isn’t working.

[plugsbands06]

I don’t know why, but when I try connecting a random walk medium to the medium part of a diffuse or universal material node, the color I changed for the radius doesn’t change color. So I’m not getting any subsurface scattering happening. I tried the same thing under the standard surface material except this time I used its own subsurface scattering that is in that node and that didn’t work either.