Bug 210635 Incorrect preview of chart after reverse categories.
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/computation/withaxes/PlotWith2DAxes.java
{
							oMax = oV2;
						}
					}
				}
			}
			else if ( ( iType & DATE_TIME ) == DATE_TIME )
			{
				if ( oV1 != null ) 
				{
					if ( oMin == null )
					{
						oMin = oV1;
					}
					else
					{
						final CDateTime cdtV1 = asDateTime( oV1 );
						final CDateTime cdtMin = asDateTime( oMin );
						if ( cdtV1.before( cdtMin ) )
						{
							oMin = cdtV1;
						}
					}
				}
				if ( oV2 != null ) 
				{
					if ( oMax == null )
					{
						oMax = oV2;
					}