DB Trigger Issue

Dear Experts,

I have created trigger that insert data into Table A from table B

but I have strange matter the code inside the trigger is not working

however if I executed this code lonely it works

So why this happen and how can I solve this

trigger code

create or replace trigger XX_OM_MNTR_MC_IMPRT_kh_Trgr

after insert on apps.XX_OM_MNTR_MC_IMPORT_HDR_TABLE

FOR EACH ROW

BEGIN

xx_om_insert_procedure;

EXCEPTION

when others then null;

END XX_OM_MNTR_MC_IMPRT_kh_Trgr;

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xx_om_insert_procedure code

find attached file