If you have configured Blackberry Enterprise Server to use EWS for calendar access and free/busy information lookup, you may encounter the following errors in the logs of the BES server:
The reason for this is that the EWS.dll assembly has not been registered in .NET Framework.
To resolve, manually register the EWS.dll assembly:
cd "\<path to Blackberry Enterprise Server directory>"
"C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\RegAsm.exe" /tlb EWS.dll" CalHelperWS.exe /regserver