Here, try following the PDF I've attached. I've never tried it; should work though. It's for version 8, but you should be able to figure it out in terms of version 7.
You can look at the firewall's audit for VPN events like this:
$> acat -ke "area vpn"
That does a 'live' audit looking only for VPN events.
I don't know anything about troubleshooting this on the Windows side.