Web page expired appears with backspace

Hi, I am working on a BSP application. This application uses pages with flow logic approach and it is a statefull app. On the screen I have a readonly field. When I place cursor on this field and click on backspace, I see page navigated to Web page expired screen. I tried using below tag but not working.

<htmlb:document disableBackspaceNavigation="TRUE" >

I have gone through below blog, but it talks about MVC.

/people/sergio.ferrari2/blog/2005/04/18/bsp-howto-back-navigation--the-nightmare-of-statefull-web-applications.

Please suggest an appropriate resolution for this error in pages with flowlogic approach.

Regards,

Siva