Subscribe to new workitems based on severity

Feb 1, 2010 at 1:45 PM

The Event subscription tool currently does not expose the severity attibute using the build button.

What expression, or xpath, can i enter into a subscription, to fire off emails, when the 'Severity' of 'Critical' is entered, into a work item change event?
The example below currently does not work:-

"CoreFields/StringFields/Field[ReferenceName='Microsoft.VSTS.Common.Severity']/NewValue" = 'Critical'

Thanks in advance