Sometimes a simple ora-01400 is just not enough, when this happens, you need to enable errorstack tracing.
alter system set events ‘1400 trace name errorstack level 3′;
Now whenever you get a ora-01400 error, a trace file will be written, to find it, simply check the alertlog.
To disable trace, use the following :-
alter system set events ‘1400 trace name errorstack off’;