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
private Button repeatHeaderButton;
	private Combo pagebreakAfterCombo;
	private Combo pagebreakBeforeCombo;
	/**
	 * Constructor.
	 * 
	 * @param parentShell
	 */
	public GroupDialog( Shell parentShell, String title )
	{
		super( parentShell, title );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.dialogs.Dialog#createDialogArea(org.eclipse.swt.widgets.Composite)
	 */
	protected Control createDialogArea( Composite parent )
	{
		
		Composite topComposite = (Composite) super.createDialogArea( parent );
		createTitleArea( topComposite );
		Composite composite = new Composite( topComposite, SWT.NONE );
		composite.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		composite.setLayout( new GridLayout( 2, true ) );
		createFieldArea( composite );
		createGroupArea( composite );
		createTOCArea( composite );
		createFilterSortingArea( topComposite );
		return topComposite;