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
return getIntervalChoiceArray( str );
	}
	private static IChoice[] getIntervalChoicesDate( )
	{
		String[] str = new String[]{
				DesignChoiceConstants.INTERVAL_NONE,
				DesignChoiceConstants.INTERVAL_YEAR,
				DesignChoiceConstants.INTERVAL_QUARTER,
				DesignChoiceConstants.INTERVAL_MONTH,
				DesignChoiceConstants.INTERVAL_WEEK,
				DesignChoiceConstants.INTERVAL_DAY,
				DesignChoiceConstants.INTERVAL_HOUR,
				DesignChoiceConstants.INTERVAL_MINUTE,
				DesignChoiceConstants.INTERVAL_SECOND
		};
		return getIntervalChoiceArray( str );
	}
	private static IChoice[] getIntervalChoicesNumeric( )
	{
		String[] str = new String[]{
				DesignChoiceConstants.INTERVAL_NONE,
				DesignChoiceConstants.INTERVAL_INTERVAL,
		};
		return getIntervalChoiceArray( str );
	}
	/**
	 * Get intervalChoiceArray
	 * 
	 * @param str
	 * @return