TRIGGER COMPILE problem .. looks EASY ??

I did a full import from 8.0.6 to 8.1.7..

Here is the trigger that fails to compile:

  1 create or replace trigger TRG.TBMDPMODBSIUD   2 before insert or update or delete on TRG.TBMDPMOD   3 declare
  4 begin
  5 sys.inf_product_check;
  6* end;
SQL> / Warning: Trigger created with compilation errors.

SQL> show errors
Errors for TRIGGER TRG.TBMDPMODBSIUD:

LINE/COL ERROR

-------- -----------------------------------------------------------------
3/1      PLS-00201: identifier 'SYS.INF_PRODUCT_CHECK' must be declared
3/1      PL/SQL: Statement ignored