Hour Burn Down chart is throwing NPE

2009-08-03 00:29:57,519 http-j2ee.jira.atlassian.com%2F127.0.0.101-8080-Processor11 ERROR bhumphreys 1797x3163x3 lkapga http://jira.atlassian.com/secure/ShowChartReport.jspa [webwork.dispatcher.ServletDispatcher] Could not execute action
java.lang.NullPointerException
	at com.pyxis.greenhopper.charts.timetracking.HourBurndown.getHeader(HourBurndown.java:321)
	at com.pyxis.greenhopper.charts.timetracking.HourBurndown.getCSVFile(HourBurndown.java:163)
	at com.pyxis.greenhopper.jira.boards.ChartBoard.getChartReport(ChartBoard.java:181)
	at com.pyxis.greenhopper.jira.actions.ChartReportAction.doShowChartReport(ChartReportAction.java:22)
	at sun.reflect.GeneratedMethodAccessor835.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at webwork.util.InjectionUtils$DefaultInjectionImpl.invoke(InjectionUtils.java:61)
	at webwork.util.InjectionUtils.invoke(InjectionUtils.java:52)
	at webwork.action.ActionSupport.invokeCommand(ActionSupport.java:417)
	at webwork.action.ActionSupport.execute(ActionSupport.java:146)
	at com.atlassian.jira.action.JiraActionSupport.execute(JiraActionSupport.java:64)
        ...