JON agent unable to load plug-in due to plug-in being corrupted

ERROR [main] (rhq.core.pc.plugin.PluginManager)- Plugin [JBossAS5] at [file:/rhq-agent/plugins/jopr-jboss-as-5-plugin-3.0.0.GA.jar] could not be loaded and will therefore not be deployed.
org.rhq.core.clientapi.descriptor.PluginTransformException: No version is defined for plugin jar [file:/rhq-agent/plugins/jopr-jboss-as-5-plugin-3.0.0.GA.jar]. A version must be defined either via the MANIFEST.MF 'Implementation-Version' attribute or via the plugin descriptor 'version' attribute.
     at org.rhq.core.clientapi.descriptor.PluginTransformer.getVersion(PluginTransformer.java:105)
     at org.rhq.core.clientapi.descriptor.PluginTransformer.toPlugin(PluginTransformer.java:70)
     at org.rhq.core.pc.plugin.PluginManager$1.execute(PluginManager.java:184)
     at org.rhq.core.pc.plugin.PluginManager.loadPlugin(PluginManager.java:339)
     at org.rhq.core.pc.plugin.PluginManager.initialize(PluginManager.java:156)
     at org.rhq.core.pc.PluginContainer.startContainerService(PluginContainer.java:372)
     at org.rhq.core.pc.PluginContainer.initialize(PluginContainer.java:245)
     at org.rhq.enterprise.agent.AgentMain.startPluginContainer(AgentMain.java:1748)
     at org.rhq.enterprise.agent.AgentMain.start(AgentMain.java:643)
     at org.rhq.enterprise.agent.AgentMain.main(AgentMain.java:413)