Download and place the following jars files in plugin folder of Cytoscape (v2.8.3):
CySBGN v1.2 depends on CySBML plug-in version 1.2 to support the automated generation of SBGN diagrams of SBML models.
Remove sbml-reader-2.8.3-jar-with-dependencies.jar from plugin folder.
CySBGN is also available in GitHub, Cytoscape App Store and Sourceforge.