Dear Jasem,
You're right, I did not give a lot of informations. Sorry.
I'm working on a laptop PC, Ubuntu 16.04.
The test I did is purely local : Kstars running on my PC, and the Indi server as well.
It worked before (few weeks ago, at least), with the same PC. I'm not sure if the problem appeared when I did upgrade to Indi/Kstars new versions, or before.