FRM-91129: fatal error: no value specified for required environment variable FORMS_BUILDER_CLASSPATH in oracle 12c R2

when open forms builder  then errors

FRM-91129: fatal error: no value specified for required environment variable 
FORMS_BUILDER_CLASSPATH

action
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Opened the Registry editor and navigated to HKLM\SOFTWARE\ORACLE\ and searched for sub keys starting with “KEY_OracleHome”. Found the correct key pointing to my installation directory and added the following string value.

string 

FORMS_BUILDER_CLASSPATH

 values

C:\oracle\Middleware\Oracle_Home\jlib\frmbld.jar;C:\oracle\Middleware\Oracle_Home\jlib\importer.jar;C:\oracle\Middleware\Oracle_Home\jlib\debugger.jar;C:\oracle\Middleware\Oracle_Home\jlib\utj.jar;C:\oracle\Middleware\Oracle_Home\oracle_common\jlib\ewt3.jar;C:\oracle\Middleware\Oracle_Home\oracle_common\modules\oracle.bali.share\share.jar;C:\oracle\Middleware\Oracle_Home\jlib\dfc.jar;C:\oracle\Middleware\Oracle_Home\oracle_common\modules\oracle.help\ohj.jar;C:\oracle\Middleware\Oracle_Home\oracle_common\modules\oracle.help\help-share.jar;C:\oracle\Middleware\Oracle_Home\oracle_common\modules\oracle.help\oracle_ice.jar;C:\oracle\Middleware\Oracle_Home\oracle_common\modules\oracle.bali.jewt\jewt4.jar;C:\oracle\Middleware\Oracle_Home\forms\java\frmwebutil.jar;C:\oracle\Middleware\Oracle_Home\forms\java\frmall.jar