What do you mean by “imported it into my Project settings”. What did you do exactly?
When I do this, it seems by default my webbrowser (which is the superior Firefox browser made by Mozilla) will only export the certificate for the website, and this will not include the chain. I can however select any certificate in the chain to export instead as well.
What your JVM will need to trust this certificate is the whole chain. I think you should explicitly export the Staat der Nederlanden Roor certificate and import that in you project settings. Maybe you need the intermediate QuoVadis cert as well, but I would think not.