Nothing happens when I launch the converter and I'm using version 12.0.3.5251
With this version of STAR*NET, if you are running with a SOLO based license (License ID and Password), and the maintenace has expired, it would fail to launch converters.
Please update to the STAR*NET 13 release, which you can download here, if your maintenance is valid for it.
Otherwise, you may need to go back to the original version 12 release in the meantime, which you can download here.
However, we would recommened updating the mainteance instead, so that you can run the latest current version which should have this issue resolved.
You can contact our sales team at: sales@microsurvey.com