categories in editor

20.04.2011 14:18:48 ERROR [org.hippoecm.frontend.model.PropertyValueProvider.addNew():124] Single-valued property can not be set to an array of values:property /content/documents/hippogagroen/events/tweeduizendelf/08/red-kite-mountain-bike-bash/red-kite-mountain-bike-bash[2]/hippogogreen:categories
javax.jcr.ValueFormatException: Single-valued property can not be set to an array of values:property /content/documents/hippogagroen/events/tweeduizendelf/08/red-kite-mountain-bike-bash/red-kite-mountain-bike-bash[2]/hippogogreen:categories
at org.apache.jackrabbit.core.PropertyImpl.checkSetValue(PropertyImpl.java:267)
at org.apache.jackrabbit.core.PropertyImpl.setValue(PropertyImpl.java:768)
at org.apache.jackrabbit.core.NodeImpl$7.perform(NodeImpl.java:2093)
at org.apache.jackrabbit.core.NodeImpl$7.perform(NodeImpl.java:2083)
at org.apache.jackrabbit.core.session.SessionState.perform(SessionState.java:200)
at org.apache.jackrabbit.core.ItemImpl.perform(ItemImpl.java:91)
at org.apache.jackrabbit.core.NodeImpl.setProperty(NodeImpl.java:2083)
at org.apache.jackrabbit.core.NodeImpl.setProperty(NodeImpl.java:1832)
at org.hippoecm.repository.decorating.NodeDecorator.setProperty(NodeDecorator.java:121)
at org.hippoecm.repository.decorating.checked.NodeDecorator.setProperty(NodeDecorator.java:160)
at org.hippoecm.frontend.model.PropertyValueProvider.addNew(PropertyValueProvider.java:97)
at org.hippoecm.frontend.editor.plugins.field.AbstractFieldPlugin.onAddItem(AbstractFieldPlugin.java:355)
at org.hippoecm.frontend.editor.plugins.field.PropertyFieldPlugin$5.onClick(PropertyFieldPlugin.java:236)
at org.apache.wicket.ajax.markup.html.AjaxLink$1.onEvent(AjaxLink.java:68)
at org.apache.wicket.ajax.AjaxEventBehavior.respond(AjaxEventBehavior.java:177)
at org.apache.wicket.ajax.AbstractDefaultAjaxBehavior.onRequest(AbstractDefaultAjaxBehavior.java:302)
at org.apache.wicket.request.target.component.listener.BehaviorRequestTarget.processEvents(BehaviorRequestTarget.java:157)
at org.apache.wicket.request.AbstractRequestCycleProcessor.processEvents(AbstractRequestCycleProcessor.java:92)
at org.hippoecm.frontend.PluginRequestCycleProcessor.processEvents(PluginRequestCycleProcessor.java:95)