The first thing to check would be the TNSNAMES.ORA file (client side).
Take a look at <a href="http://searchoracle.techtarget.com/answer/Resolving-the-TNS-12502-error">this SearchOracle article</a>.
Last Wiki Answer Submitted: February 11, 2010 2:00 pm by carlosdl63,535 pts.
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