The module or table must be properly set up for change data capture. In addition, default agent must be configured with password and the module location must be registered.
executeCDCCommand =  OMBCDC ( ( ORACLE_MODULE | MODULE | TABLE ) 
          "QUOTED_STRING" ( START_CDC | DROP_CDC | EXTEND_WINDOW | ( SUBSCRIBE 
          "QUOTED_STRING" ) | ( UNSUBSCRIBE "QUOTED_STRING" ) | ( 
          LOCK_SUBSCRIBER "QUOTED_STRING" ) | ( UNLOCK_SUBSCRIBER 
          "QUOTED_STRING" ) | GET_SUBSCRIBERS | PURGE_CDC ) )