Can't display edit mode in GateIn

Hi guys,

I wrote a portlet(JSR 168) step by step via the Vaadin book and deploy it on GateIn(3.1.0-GA). The view mode works well, but the edit mode is empty except I refresh the edit page(in edit page layout page, click the edit pencil) while holding Shift key. I also deploy the demo portlet to GateIn, and the edit mode is empty too. Is anybody encountered this problem? or Has anybody deploy portlet on GateIn with edit mode written in Vaadin suceessfuly?

I am new to Vaadin and GateIn, any info are appreciated, thanks in advanced.

ps I am using vaading 6.4.8 and test it in Firefox 3.6