UDE-00018 Error when trying to use Data Pump in Oracle Enterprise 11.2.0.1

This system has been in place for 2 years, and I suddenly have need to export some data.  When attempting to do expdp, I get the following error:
UDE-00018: Data Pump client is incompatible with database version 11.2.0.1.0

However, the expdp release is:
Export: Release 11.2.0.1.0 - Production on Fri Dec 7 15:55:45 2012

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

All the other versions are:
BANNER
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Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE    11.2.0.1.0      Production
TNS for Linux: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production

This database was initially created at this release, never upgraded.