Can't add directoryOperation attribute type

["Chris Brook" <cbrook@v-one.com>]

I need to add an attribute type: accessTimeStamp which is exactly like
createTimeStamp and modifyTimeStamp but slapd refuses it with the error:
attribute type "xx.xx....xx" is operational
and shuts down.  I have defined the attribute type as SINGLE-VALUE
NO-USER-MODIFICATION USAGE directoryOperation.  Is this not allowed in a
schema included via slapd.conf.  Is there any way to get around this?
Chris Brook