cannot access components by another desktop

<borderlayout id="main" apply="com.zkdesktop.web.MainLayoutComposer" width="100%" height="100%">
	<north border="0" flex="true" margins="0,0,0,0"><label>Header</label></north>
	<center id="mainContent" autoscroll="true" border="normal" flex="true" margins="0,0,0,0"></center>
	<south border="0" flex="true" margins="0,0,0,0"><label>Footer</label> </south>
</borderlayout>

public class MainLayoutComposer extends GenericForwardComposer {
	
	....

	public void doAfterCompose(Component comp) throws Exception {
		super.doAfterCompose(comp);
		ZKPageUtil.setComponent(comp);
		Map<String, Object> params = new HashMap<String, Object>();
		params.put("url", "main");
	
		ZKPageUtil.sendRedirectURL("/pages/main.zul", params);
	}
	
	.....

}

public class ZKPageUtil {

	.....

	public static void setComponent(Component component) {
		ZKPageUtil.component = component;
	}

	public static void sendRedirectURL(String filename, Map<String, Object> params) {
		String bookmark = (String) params.get("url");
		
		try {
			if(component != null) {
				final Center mainContent = (Center) component.getRoot().getFellow("mainContent");
				Components.removeAllChildren(mainContent);
				
				Executions.getCurrent().getDesktop().setBookmark(bookmark);
				Executions.createComponents(filename, mainContent, params);
			}
		} catch (Exception e) {
			_log.warn(e.getMessage(), e);
		}
		
	}

	....
}