In seldom cases, the Outlook Web Sensor produces the following error related to the Calendar Lookup Simulation:

OutlookWeb: lookup for user <username> failed with error System.Exception: Proxy web request failed. , inner exception: System.Web.Services.Protocols.SoapException: Periods have duplicate IDs.

Solution

Adjust the Outlook Web Sensor:

• Open the Outlook Web Sensor
• Select the following item in the Exchange Version field

Exchange 2007 SP1

• Save
• Click on Deploy Sensor Configuration