Throw NullPointerException when clicking into "Time Tracking Analysis" of Burndown Chart

java.lang.NullPointerException
at com.atlassian.greenhopper.web.chart.action.TimelineAnalysisRenderer.getFormattedInitialRemainingEstimate(TimelineAnalysisRenderer.java:104)
at sun.reflect.GeneratedMethodAccessor309.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
...