Anchor on ligature

For some reason I can place an anchor in a ligature. So I copied and pasted one from another glyph. As i click on the placed anchor, no preview of any mark appears.

In ligatures, the anchors need a number suffix, one for each component: top_1, top_2, …

Thanks Georg,
And respectivly, what number do I need to add to the components to make the linkage?

The components don’t need numbers.
If you select an accent/mark component, there is an anchor symbols in the info box. Click on it and you get an menu to pick the anchor you like to attache to.