Merge statement

Hello Experts,
I have a script to do merging if the two tables' information are match and if not then do the update.  I don't know what I did wrong, would you please help out?
create or replace FUNCTION "ECISDRDM"."PR_MIG_STG_APPL_CDIM" (v_Ret OUT bigint )as $$declare         v_ErrorCode             bigint;        v_ErrorMsg              varchar(512);        v_Module                varchar(32) = 'PR_MIG_STG_APPL_CDIM';
begin
   ----   -- MERGING: STG_APPLICATION_CDIM into APPLICATION_CDIM   ----   MERGE INTO "ECISDRDM"."APPLICATION_CDIM" prod   USING (   SELECT Receipt_Number,application_id, init_frm_id, frm_typ_id, init_src_sys_id, init_svc_ctr_id, crtd_user_id, sbmtd_dt_id, mig_filename, mig_modified_dt   FROM stg_application_cdim    ORDER by mig_filename ) stg   ON ( prod.receipt_number = stg.receipt_number )   WHEN MATCHED THEN UPDATE SET      prod.application_id       = stg.application_id,      prod.init_frm_id         = stg.init_frm_id,      prod.frm_typ_id         = stg.frm_typ_id,      prod.init_src_sys_id      = stg.init_src_sys_id,      prod.init_svc_ctr_id      = stg.init_svc_ctr_id,      prod.crtd_user_id         = stg.crtd_user_id,      prod.sbmtd_dt_id         = stg.sbmtd_dt_id,      prod.mig_filename         = stg.mig_filename,      prod.mig_modified_dt      = current_timestamp   WHEN NOT MATCHED THEN INSERT   (prod.Receipt_Number, prod.application_id, prod.init_frm_id, prod.frm_typ_id, prod.init_src_sys_id, prod.init_svc_ctr_id, prod.crtd_user_id, prod.sbmtd_dt_id, prod.mig_filename ) SELECT ( stg.Receipt_Number, stg.application_id, stg.init_frm_id, stg.frm_typ_id, stg.init_src_sys_id, stg.init_svc_ctr_id, stg.crtd_user_id, stg.sbmtd_dt_id, stg.mig_filename           )   ;
   ----   -- Set the return code to 0   ----
   v_Ret := SQLCODE;
------ Exception error handler----exception   when others then v_ErrorCode := SQLCODE; v_ErrorMsg  := SQLERRM; v_Ret       := v_ErrorCode;
---- -- Commit the record into the ErrorLog ---- pr_write_error_log( sys_context('userenv','session_user'), sys_context('userenv','host'),    v_Module, v_ErrorCode, v_ErrorMsg );
                ----                -- Intentionally leaving the "commit" to application                ----end;$$ language plpgsql;

ERROR:  "application_cdim" is not a known variableLINE 13:    MERGE INTO APPLICATION_CDIM prod                       ^SQL state: 42601Character: 349

even I take schema_name, ECISDRDRM out, I still get an error:
ERROR:  "application_cdim" is not a known variableLINE 13:    MERGE INTO APPLICATION_CDIM prod                       ^SQL state: 42601Character: 349

thank you for your help.
v/r,
Bach-Nga

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