How to use virtual feed back ?

[ebarra]

Hello,
I am trying to use a virtual K84 Symbol Switch to use its virtual feed back adress as a switching condition for a  route. (see picture attached).
Unfortunately the Virtual FB 153 is not seen by the Route switch conditions even a track feed back does not sees the adress 153.
1) is there any track Symbol allowing to simulate a real feed back?
2) What are these virtual feed back for?
3) How these Virtual feed back can be used?

Regards.