Bug 118738 can't preview meter chart with grouping
Try to preview the following report with a meter chart group on the Y series, it fails. It used to work before, this is a regression. An exception is thrown org.eclipse.birt.chart.exception.ChartException: Can not plot meter series with null or non-numeric datapoint. at org.eclipse.birt.chart.render.DialRenderer.<init>(DialRenderer.java:132) at org.eclipse.birt.chart.render.Dial.compute(Dial.java:98) at org.eclipse.birt.chart.factory.Generator.build(Generator.java:759)
chart/org.eclipse.birt.chart.device.extension/src/org/eclipse/birt/chart/device/image/JavaxImageIOWriter.java
{
				it = null; 
			}
		}
		
		if ( it == null )
		{
			s = getMimeType( );
			if ( s == null )
			{
				throw new ChartException( ChartDeviceExtensionPlugin.ID,
						ChartException.RENDERING,
						"exception.no.imagewriter.mimetype.and.format",
						new Object[]{
								getMimeType( ),
								getFormat( ),
								getClass( ).getName( )
						},
						ResourceBundle.getBundle( Messages.DEVICE_EXTENSION,
								getLocale( ) ) );
			}
			it = ImageIO.getImageWritersByMIMEType( s );
			if ( !it.hasNext( ) )
			{
				throw new ChartException( ChartDeviceExtensionPlugin.ID,
						ChartException.RENDERING,
						"exception.no.imagewriter.mimetype", 
						new Object[]{
							getMimeType( )
						},