Packages installed in java environment not found in Servoy

I have installed a third party java library (RXTXComm.jar and some dlls) in the java environment as an extension in the system library, but I can’t see or access it from within Servoy. From a java application it works. Is there something special I have to do to make it available in Servoy?

what is servoy?
are we talking here about the developer?

or a smart client? or the application server?