We're having problems getting iPhones to sync properly with SBS 2003 Exchange.

When you add a new Exchange ActiveSync account on an iPhone and enter all the pertinent information, it shows a "Verifying Exchange account info" message for a minute or so, then says everything's verified and asks what you want to sync, Mail, Contacts, Calendars... so it looks like it's working.

However, when you go to the Mail app and select the Exchange email account, it just shows an "Inbox" folder with nothing in it. When you try refreshing, it attempts for a second, then says "Last Updated" with a timestamp, as if it worked, but there's no mail and no error message/feedback at all.

I think I've narrowed it down to some sort of certificate issue, but I'm having trouble finding out where to go from here... I ran MS's Exchange connectivity testing tool with these results:

Our cert was purchased from Network Solutions, and I'd already added it to the IIS Default Website for OWA purposes. But this report makes it look like the cert is somehow problematic. I don't know what to do now...

Here's a shot of the cert details, just in case: