I try to copy a geometry to some of the points of another geometry. In the attached example I connect a sphere as point provider to CopyToPoints and a box as the geometry to copy. This works fine (left network).
My approach to copy the box only to some points of the sphere is to insert a Group between the Sphere and CopyToPoints. For the ease of the example I simply selected 50% of the points randomly. This does not work (right network). CopyToPoints complains that the group is invalid.
I do not understand why. Maybe someone can explain this to me and tell me how to solve this.

2 issues

1. your group is a primitive group instead of point group
2. you specified it as Source Group in Copy while you want to specify it in Target Group field