RichFaces dataGrid Radio Button

Assuntos Gerais
#1

Olá pessoal, estou com um problema quando estou datagrid e radio button.
Tenho um bean que tem um metodo que tenta pegar a linha do selectOne com o método getRowData() do DataGrid.
Se alguém puder ajudar desde já agradeço. o problema que dá está depois do código.
Ele entra no método e como eu disse, da erro na primeira linha.

<rich:dataGrid value="#{questao.alternativas}"
	binding="#{bean.htmlDataGridAlternativa}"
	var="alternativa"
	columns="1" elements="5">
	<h:selectOneRadio value="#{bean.codAlternativaSelecionado}">
		<f:selectItem itemValue="#{alternativa.codAlternativa}"
			itemLabel="#{alternativa.texto}" />
	</h:selectOneRadio>
		<a4j:support eventsQueue="a" 
			event="onclick"
			actionListener="#{bean.resolverQuestao}"/>
</rich:dataGrid>

METODO:

private HtmlDataGrid htmlDataGridAlternativa;

	public void resolverQuestao(ActionEvent event){
		htmlDataGridAlternativa.getRowData();
		Alternativa alt = null;
		codAlternativaSelecionado = alt.getCodAlternativa();
		if(alt.isCorreta()){
			System.out.println("ACERTOU");
		}else{
			System.out.println("ERROU");
		}
	}

09/07/2010 21:26:13 org.ajax4jsf.component.AjaxViewRoot processEvents
SEVERE: Error processing faces event for the component j_id_jsp_2017684010_5:j_id_jsp_2017684010_6:0
javax.faces.event.AbortProcessingException: /helloWorldRichFaces.jsp(57,2) ‘#{bean.resolverQuestao}’ java.lang.IllegalArgumentException
at javax.faces.event.MethodExpressionActionListener.processAction(MethodExpressionActionListener.java:118)
at javax.faces.event.ActionEvent.processListener(ActionEvent.java:88)
at javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:766)
at javax.faces.component.UICommand.broadcast(UICommand.java:372)
at org.ajax4jsf.component.AjaxActionComponent.broadcast(AjaxActionComponent.java:55)
at org.ajax4jsf.component.UIDataAdaptor.broadcast(UIDataAdaptor.java:1359)
at org.ajax4jsf.component.UIDataAdaptor.broadcast(UIDataAdaptor.java:1359)
at org.ajax4jsf.component.AjaxViewRoot.processEvents(AjaxViewRoot.java:317)
at org.ajax4jsf.component.AjaxViewRoot.broadcastEvents(AjaxViewRoot.java:292)
at org.ajax4jsf.component.AjaxViewRoot.processPhase(AjaxViewRoot.java:249)
at org.ajax4jsf.component.AjaxViewRoot.processApplication(AjaxViewRoot.java:462)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:265)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:154)
at org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:260)
at org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:366)
at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:493)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IllegalArgumentException
at javax.faces.model.ListDataModel.getRowData(ListDataModel.java:150)
at org.ajax4jsf.model.SequenceDataModel.getRowData(SequenceDataModel.java:147)
at org.ajax4jsf.component.UIDataAdaptor.getRowData(UIDataAdaptor.java:258)
at dominandoquestoes.bean.Bean.resolverQuestao(Bean.java:27)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.el.parser.AstValue.invoke(AstValue.java:191)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276)
at org.apache.jasper.el.JspMethodExpression.invoke(JspMethodExpression.java:68)
at javax.faces.event.MethodExpressionActionListener.processAction(MethodExpressionActionListener.java:99)
… 32 more

#2

ALguém vivo???

#3