Dev2K error, probably simple

I'm just getting started with Developer 2000. When I create a simple form and try to compile it, I get the following error:

Error 0 at line 0, column 0
  ORA-04029 ; error ORA-904 occurred when querying ORA_KGLR7_IDL_SB4

This is in the ON-CHECK-DELETE-MASTER trigger.

The error occurs in one of the master data blocks for the form.

Any idea what's going on?

Oh, the tables and relationships in question were originally created using ERWin 2.5. Looking

Thanks for the help.

-- 
    Day's never finished,
    Master's got me working,
    Someday Master set me free