I couldn't find this anywhere on the web so I thought I would post it here.

I had an issue where I setup Active Synch on my Exchange server, setup the Treos, and only the mail would synch. The calendar would say it was synching but would never show up. After searching all over the web and calling Verizon (who said it couldnt be done) I finally called Microsoft and opened a case. It turned out that I had installed an older version of URLScan (v2.5 I think) on the exchange server that wasn't 'Exchange aware'. The log was malfunctioning and not showing anything but it was blocking the IF: statements for the calendar function. It still didn't work after editing the .ini file so I ended up uninstalling it. It's not recommended for Exchange nor 2003 servers anyhow (that security is built-in) but I did it out of habit. Just an FYI for anyone who runs into this problem and is overly security conscious like me.