Session state timing out in 20 min. regardless of web.config

[JJ]

I have an asp.net 1.1 app I wrote using the Mobile Controls.

I changed the timeout attribute in sessionState in web.config from the
default of 20 to 1440:

<sessionState
mode="InProc"
cookieless="fal se"
timeout="1440"
/>

So I would expect that the sessions would not time out for an entire day (60
* 24 = 1440 minutes). But they are still timing out in 20 minutes. I also
changed machine.config just in case, but no help.

I put code in the app to display Session.Timeout , and it is displaying 1440,
so it sees my web.config settings.

But if I open a page in my app (via the browser on a Blackberry) and let it
sit for more than 20 minutes and then click a button in the app, I get an
exception:

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.

History size is not the issue (I upped that to 50, but it works fine if I
click before 20 minutes). The KB article about anti-virus software causing
this is not the issue because there is no anti-virus software running on the
web server.

Does the 20 minute timeout need to be changed somewhere else? Is it hard
coded somewhere for mobile forms?