This is a simple symptom-cause-solution blog entry only. I hope these blogs will help fellow administrators.
In WebLogic 9.2, adding an account to the Operator group has no effect if the account is also added to another group.
This is a known bug in WebLogic 9.2.
A patch is provided with the 9.2 installation. Ensure %BEA_HOME%\patch_weblogic920\patch_jars\CR285163_920GA.jar; is on the classpath.