path to image does not work when published on app portal

[curiousfellow]

I have an expression like this :
if (value > 2000, 'green.png', 'red.png'). The representation of this expression is set to 'image'
This works fine when developing.
However when I publish this app on a server, and the app is accessed through the portal only the filename is shown as text.

Why doesn't this work ? 
I tried a lot of options :

- with relative paths
- bundle load
- with and without comma's
- path an filename as variable

- with and without apostrophe

This is the last problem to solve before I can publish my app to a larger audience, but I cannot solve this puzzle.

In some topics I read that relative paths have to be enabled, but cannot find an option to do that

We use Qlikview May 2021 SR1