The associated radiobutton gives me an error

[sebasvanderplaat]

java.lang.NullPointerException: null
at com.mendix.webui.actions.ActionUtil$.com$mendix$webui$actions$ActionUtil$$hasNoVirtualAttributes(ActionUtil.scala:66)
at com.mendix.webui.actions.ActionUtil$$anonfun$buildSortMap$1.apply(ActionUtil.scala:42)
at com.mendix.webui.actions.ActionUtil$$anonfun$buildSortMap$1.apply(ActionUtil.scala:39)
at scala.collection.immutable.Range.foreach(Range.scala:160)
at com.mendix.webui.actions.ActionUtil$.buildSortMap(ActionUtil.scala:39)
at com.mendix.webui.actions.ActionUtil$.buildSortMap(ActionUtil.scala:32)
at com.mendix.webui.actions.ActionUtil$.addSortExpressions(ActionUtil.scala:107)
at com.mendix.webui.actions.client.XPathRetriever.retrieveWithoutSchema(XPathRetriever.scala:101)
at com.mendix.webui.actions.client.RetrieveByXPathAction.execute(RetrieveByXPathAction.scala:39)
at com.mendix.webui.requesthandling.ClientRequestHandler$$anonfun$handleRequest$1.apply$mcV$sp(ClientRequestHandler.scala:324)
at com.mendix.webui.requesthandling.ClientRequestHandler$$anonfun$handleRequest$1.apply(ClientRequestHandler.scala:317)
at com.mendix.webui.requesthandling.ClientRequestHandler$$anonfun$handleRequest$1.apply(ClientRequestHandler.scala:317)
at com.mendix.core.session.Worker$$anonfun$receive$3$$anonfun$2$$anon$1.execute(ActionDispatching.scala:144)
at com.mendix.util.classloading.Runner.doRunUsingClassLoaderOf(Runner.java:32)
at com.mendix.core.session.Worker$$anonfun$receive$3$$anonfun$2.apply(ActionDispatching.scala:146)
at scala.util.Try$.apply(Try.scala:191)
at com.mendix.core.session.Worker$$anonfun$receive$3.applyOrElse(ActionDispatching.scala:140)
at akka.actor.Actor$class.aroundReceive(Actor.scala:465)
at com.mendix.core.session.Worker.aroundReceive(ActionDispatching.scala:136)
at akka.actor.ActorCell.receiveMessage(ActorCell.scala:516)
at akka.actor.ActorCell.invoke(ActorCell.scala:487)
at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:238)
at akka.dispatch.Mailbox.run(Mailbox.scala:220)
at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:393)
at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)