My problem is that long node labels do reach on both sides over the end of the node

This only occurs with node-shapes like rectangle, square, tab or similar but never with oval,circle or diamond.
I am using the Java Graphviz-Engine (guru-nidi:graphviz-java:0.14.1) and my corresponding code (simplified) is the following:
String graphString =
digraph g {
extralargesubject [shape=diamond];
extralargeobject [shape=rectangle] ;
extralargesubject -> extralargeobject;
}
and
import guru.nidi.graphviz.engine.Format;
import guru.nidi.graphviz.engine.Graphviz;
import guru.nidi.graphviz.model.MutableGraph;
import guru.nidi.graphviz.parse.Parser;
MutableGraph g = new Parser().read(graphString);
BufferedImage image = Graphviz.fromGraph(g).render(Format.SVG).toImage();
Maybe someone can help me with this problem?
Ok, I found the solution. I only worked with the .jar. But that's only the Engine. Of course I had to install Graphviz also on my machine. Now I did and everything works now fine!