Bug 212370 [Regression] Negative value can not be shown both in chart builder and when preview [13]
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/computation/withaxes/PlotWith2DAxes.java
iDataSetCount = dsi[iSeriesIndex].size( );
						final AxisSubUnit au = ssl.getSubUnit( sg, k );
						for ( int j = 0; j < iSeriesPerGroup; j++ )
						{
							se = (Series) alSeriesPerGroup.get( j );
							if ( j > 0 ) 
							{
								if ( dsi[iSeriesIndex] == null )
								{
									ds = se.getDataSet( ); 
									dsi[iSeriesIndex] = new DataSetIterator( ds );
									
									dsi[iSeriesIndex].reverse( cwa.isReverseCategory( ) );
									
									if ( ( dsi[iSeriesIndex].getDataType( ) & IConstants.NUMERICAL ) != IConstants.NUMERICAL )
									{
										throw new ChartException( ChartEnginePlugin.ID,
												ChartException.DATA_SET,
												"exception.percent.stacked.non.numerical",  
												Messages.getResourceBundle( rtc.getULocale( ) ) );
									}
								}
							}
							
							oValue = dsi[iSeriesIndex].next( );
							if ( oValue != null ) 
							{
								
								double dValue = ( (Double) oValue ).doubleValue( );