VIewexpiredexceptionin jsf with viewscope bean.

Hi,
I have face viewexpired exception in jsf application.
I have added managed bean as @viewscope.
And,i have added the entery in web.xml as serialize_state__session as false
and also i added state saving method to client.
Though i have face issue in prod server,once i try to hit any button.
I have this issue for more than a week.
Thanks in advance.
Kindly help me on this issue,.
Its a great help if u did.