Bug 136027 [Smoke]the report with a gounp can not preview
Description: the report with a gounp can not preview Steps to reproduce: 1. new a datasource and a dataset 2. drag the dataset to the layout 3. Add a group on the table. save and preview. Actual result: "Error happened while running the report" is appeared.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/GroupDialog.java
* The include check box and sorting direction radio box
	 */
	private Button includeHeader, includeFooter, ascending, descending;
	private Button intervalBaseButton;
	private Text intervalBaseText;
	private Button hideDetail;
	private Text tocEditor;
	final private static IChoice[] intervalChoicesAll = DesignEngine.getMetaDataDictionary( )
			.getChoiceSet( DesignChoiceConstants.CHOICE_INTERVAL )
			.getChoices( );
	final private static IChoice sortByAscending = DesignEngine.getMetaDataDictionary( )
			.getChoiceSet( DesignChoiceConstants.CHOICE_SORT_DIRECTION )
			.findChoice( DesignChoiceConstants.SORT_DIRECTION_ASC );
	final private static IChoice sortByDescending = DesignEngine.getMetaDataDictionary( )
			.getChoiceSet( DesignChoiceConstants.CHOICE_SORT_DIRECTION )
			.findChoice( DesignChoiceConstants.SORT_DIRECTION_DESC );
	final private static String SORT_GROUP_TITLE = DEUtil.getPropertyDefn( ReportDesignConstants.TABLE_GROUP_ELEMENT,
			GroupHandle.SORT_DIRECTION_PROP )
			.getDisplayName( );
	final private static IChoice[] pagebreakBeforeChoicesAll = DesignEngine.getMetaDataDictionary( )
			.getChoiceSet( DesignChoiceConstants.CHOICE_PAGE_BREAK_BEFORE )
			.getChoices( );
	final private static IChoice[] pagebreakAfterChoicesAll = DesignEngine.getMetaDataDictionary( )
			.getChoiceSet( DesignChoiceConstants.CHOICE_PAGE_BREAK_AFTER )
			.getChoices( );
	final private static IChoice[] intervalChoicesString = getIntervalChoicesString( );
	final private static IChoice[] intervalChoicesDate = getIntervalChoicesDate( );
	final private static IChoice[] intervalChoicesNumeric = getIntervalChoicesNumeric( );
	private static IChoice[] intervalChoices = intervalChoicesAll;
	private String previoiusKeyExpression = "";