How to insert a component in the right icon at AppBar?

I used a stack in my right icon in the Appbar (2 icons, with 'condition'). Then, I converted it to a component.

At this point, ok. Working well.

But I can´t reuse this component on other pages. When I try to drop this component at that point, no space is shown:

If I try an icon, the space appears:

How can I insert this component in that place?