Effects with palletes

Hi,

I am trying to create an effect on two colours, l180 and l105.
When I use the group, then effect @ colour 52 through colour 53 .
I will see these two colours, but also other colours , that I do not want. How to do this in a easy way?

Can I give the colours in this effect a different path and length?
I want colour 52 to snap
Colour 53 to fade linear out.

Thanks