I think this is a common issue with wireless calendar sync. Outlook to the handheld calendar works fine, blackberry to outlook not as well.... I've seen several hot fixes or service packs for the BES that show this being fixed but it still continues to happen. What was explained to me is that the calendar entries from the BB to outlook can get "lost" due to the priorities of the device. Incoming mail first, then outgoing and then calendar etc... If signal strength is low when it gets to calendar entries they get dropped. I have had users complain about it but when I test it works like 99.95% of the time. This used to be blamed on BES/exchange permissions and cdo.dll files too... Frustrating but I have not seen a consistent fix!!