Session state problem in mobile web application.

[JuneT]

Has anyone encountered the error as follows:

"The page requires session state that is no longer available. Either the
session has expired, the client did not send a valid session cookie, or the
session state history size is too small. Try increasing the history size or
session expiry limit. "

Our mobile web application runs perfectly on asp.net 1.1 on top of
iis6/w2k03...We then decided to migrate to asp.net 2.0, recompiled and
redeployed the application and bang, the error above occurs...

any clues as to why?

thanks!

JuneT