Perch:success content missing

I've never been able to get the following content region to appear anywhere in our perch admins and wondered if someone could shed some light on how this bit actually works?

<perch:success>
  <perch:content id="thankyou" label="Success message" type="textarea" textile="true" editor="markitup" />
</perch:success>

We always end up replacing the perch:content tag with a hardcoded error message that the admin cannot edit. We have never figured out how to make this actually show up anywhere to be able to edit the text.

Thanks in advance!