Thought I would post this, seeing as it happens and people cannot seem to find the answer. Of course I refer to appointments not syncing from BB to Outlook.

First off, in order for the Calendar to work it needs proper permissions. Your first thought might be to use an admin account. Who has better access than an admin right? Well in this case the admin loses the Send as rights needed to access the calendar, thus making it not work. Remember that the Calendar works like email, so permissions are a factor, unlike Address Book/Memos/Tasks.

Here are the common things to look for with this issue:

1. Make sure that CDO.dll is the same version or higher than the Exchange version
a) Search for CDO.dll on both BES and Exchange
b) If the version on the BES is lower, then unregister it and copy the one from
Exchange and register it
i) Navigate to the CDO.dll directory in a command prompt and type
'regsvr32 -u cdo.dll'
ii) Next, copy the newer CDO.dll into the system32 directory and run
'regsvr32 cdo.dll' from the command line to register it
c) Restart the Dispatcher service

2. Permissions, Permissions, Permissions

a) Check group membership for your BESAdmin account. It cannot be in admin
groups. The ONLY exception to the rule is when your BES is on a DC. In this
case you need to add the BESAdmin to the built-in admins group to get local
admin privileges

b) This KB should be used to verify permissions in ESM:
i) KB02276 - Assigning permissions for a BlackBerry Enterprise Server service account

c) If you have double and triple checked permissions and the Calendar still does
not work then try the following:

i) Add an appointment in the Calendar on the BB and then check the MAGT
log from the bottom up for that users email address or for CDO, you
should see some lines like these

ii) [3] (12/06 00:10:19):{0x7EC} *** CDO *** CDOCalendar::Initialize(...) -
Code = 80040705, WCode = 0505, Code meaning = IDispatch error #1285,
[3] (12/06 00:10:19):{0x7EC} Server = laexch, Mailbox = /o=CompanyX
/ou=First Administrative Group/cn=Recipients/cn=User Description =
You do not have permission to log on. [Microsoft Exchange Server
Information Store - [MAPI_E_FAILONEPROVIDER(8004011D)]].
[4] (12/06 00:10:19):{0x7EC} MAPIMailbox::SetCalendarSyncSupport -
CDOCalendar Initialize failed for User

iii) That line means that permissions are still a factor, if so, perform a switch
service account - KB04293 - How to switch BlackBerry Enterprise Server service accounts

3. The Exchange Public Folder database is not mounted. If that is the case, then mount it. Problem solved

Here is RIM's KB on this as well:

KB05270 - One-way wireless calendar synchronization for one or more BlackBerry users

There are other causes for this issue but these are the most common and often times the most missed.

Feel free to post any other fixes/tips that you may have encountered or correct anything I may have screwed up. Yes, it does happen from time to time