gvSIG sensors

ERROR [AWT-EventQueue-1] (NotificationManager.java:107) - Error guardando el proyecto: kk.gvsproj
Error getting or setting the state of an object.
The type expected for FFrameChart.assoc_chart is String and is org.gvsig.app.project.documents.chart.ChartDocument.
Errors found validating persistent state.
Errors found validating 'org.gvsig.project.documents.layout.frames.FFrameChart'.
Errors found validating 'Persistence:FFrameChart'.
Field 'assoc_chart': Value required.
org.gvsig.tools.persistence.exception.PersistenceException: Error getting or setting the state of an object.
The type expected for FFrameChart.assoc_chart is String and is org.gvsig.app.project.documents.chart.ChartDocument.
Errors found validating persistent state.
Errors found validating 'org.gvsig.project.documents.layout.frames.FFrameChart'.
Errors found validating 'Persistence:FFrameChart'.
Field 'assoc_chart': Value required.
at org.gvsig.tools.persistence.impl.DefaultPersistentContext.addError(DefaultPersistentContext.java:371)
at org.gvsig.tools.persistence.impl.AbstractPersistentState.getObjectToPersist(AbstractPersistentState.java:594)
at org.gvsig.tools.persistence.impl.AbstractPersistentState.set(AbstractPersistentState.java:339)
at org.gvsig.project.documents.layout.frames.FFrameChart.saveToState(FFrameChart.java:118)
at org.gvsig.tools.persistence.impl.SimplePersistenceFactory.saveToState(SimplePersistenceFactory.java:138)
at org.gvsig.tools.persistence.impl.AbstractPersistenceManager.createState(AbstractPersistenceManager.java:311)
at org.gvsig.tools.persistence.impl.AbstractPersistentState.getObjectToPersist(AbstractPersistentState.java:508)
at org.gvsig.tools.persistence.impl.AbstractPersistentState.getObjectToPersist(AbstractPersistentState.java:460)
at org.gvsig.tools.persistence.impl.AbstractPersistentState.storeValues(AbstractPersistentState.java:661)
at org.gvsig.tools.persistence.impl.AbstractPersistentState.getObjectToPersist(AbstractPersistentState.java:562)
at org.gvsig.tools.persistence.impl.AbstractPersistentState.set(AbstractPersistentState.java:351) ...