Receiving ConcurrentModificationException (40633)

We have a chart that refreshes every two minutes. The data is loaded to the chart via a servlet. The chart datasource is an input stream and the data is in an array format. On initial load the chart and all labels work fine. When the chart refreshes we get a series of the error message below repeated. I tried to removeAllLabels when I refresh and readd them but it did not seem to help. How do I fix this error?

Exception in thread "AWT-EventQueue-2" java.util.ConcurrentModificationException
at java.util.AbstractList$Itr.checkForComodification(Unknown Source)
at java.util.AbstractList$Itr.next(Unknown Source)
at com.klg.jclass.chart.JCDefaultChartLabelManager.paintConnectors(Unknown Source)
at com.klg.jclass.chart.JCChart.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at com.klg.jclass.chart.JCChart.paint(Unknown Source)
at javax.swing.JComponent.paintWithOffscreenBuffer(Unknown Source)
at javax.swing.JComponent.paintDoubleBuffered(Unknown Source)
at javax.swing.JComponent._paintImmediately(Unknown Source)
at javax.swing.JComponent.paintImmediately(Unknown Source)
at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(Unknown Source)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)