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
intervalType.add( intervalChoices[i].getDisplayName( ) );
		}
		intervalType.setData( intervalChoices );
		intervalType.addSelectionListener( new SelectionAdapter( ) {
			public void widgetSelected( SelectionEvent e )
			{
				intervalRange.setEnabled( intervalType.getSelectionIndex( ) != 0 );
				intervalBaseButton.setEnabled( intervalType.getSelectionIndex( ) != 0
						&& ( getColumnType( ) != String.class ) );
				intervalBaseText.setEnabled( intervalBaseButton.getEnabled( )
						&& intervalBaseButton.getSelection( ) );
			}
		} );
		
		intervalRange = new Spinner( intervalRangeArea, SWT.NONE );
		intervalRange.setLayoutData( new GridData( GridData.HORIZONTAL_ALIGN_FILL ) );
		intervalRange.setMinimum( 0 );
		intervalRange.setMaximum( Integer.MAX_VALUE );
		intervalRange.setStep( 1 );
		
		intervalBaseButton = new Button( composite, SWT.CHECK );
		intervalBaseButton.setText( GROUP_DLG_INTERVAL_BASE_LABEL ); 
		intervalBaseButton.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		intervalBaseButton.addSelectionListener( new SelectionAdapter( ) {
			public void widgetSelected( SelectionEvent e )
			{
				intervalBaseText.setEnabled( intervalBaseButton.getSelection( ) );
			}
		} );
		intervalBaseText = new Text( composite, SWT.SINGLE | SWT.BORDER );