How to get indicator from HandleUIMessage vi to Top Level.vi

[Skoda3]

I want to custumize Simple user interface for testand (Labview). 

I read all of this:

https://www.ni.com/en/support/documentation/supplemental/14/working-with-the-teststand-simple-user-i...

At the : "Handling additional events" there shows how to create callback vi so that we can do some event handling code when UI message comes:

 But If I put some boolean indicator here inside and connect it to connector pane to be used for example to indicate some event is done, i get broken Wire:

Why this is happening and how to get this indicator to the top level vi?

[AndreasGareis]

Hello Skoda3,

your Callback VI reference breaks probably because you added your boolean indicator to the connector pane. That changes the VI reference for the callback VI and is not compatible with the event. Also, these callback VI's are called outside of the flow of data and you would not benefit from that indicator. Rather, implement a different communication approach using queues or user events in LabVIEW to transfer data from the callback VI back to your main application.

Best regards