Follow KB -http://support.microsoft.com/kb/300956/en-us?wa=wsignin1.0
If that doesn't work Try the workaround below ;worked for me in Lab :
1. Start EMS
2. add-pssnapin Microsoft.Exchange.Management.PowerShell.Setup
3. new-perfcounters –definitionfilename "C:\Program Files\Microsoft\Exchange Server\V14\Setup\Perf\RpcClientAccessPerformanceCounters.xml"
Ref: blog about adding missing perf counters in Exchange 2010:
http://blogs.technet.com/b/mikelag/archive/2010/09/10/how-to-unload-reload-performance-counters-on-exchange-2010.aspx
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If this resolved the issue don't forget to Click on Green tab and keep me motivated !!!
Anand Shankar