charset problems with db/400

Hello,

I've come across very strange problem.
If Java program runs at iSeries and uses type 2 JDBC from
db2_classes.jar to access tables, string operands are updated with
really weird strings, like "...,.,,." (or even worse) instead of
specified value. Of course when subseqent select(s) are trying to
retrieve this data, it doesn't work. 

The same update from STRSQL console is pretty OK 

The same Java code on the same iSeries with type 4 JDBC (from JT400) is
also OK

The same Java code on other AS/400s is sometimes OK, but sometimes not. 
But when the database with problems is copied through SAVF to another
AS/400 where it is OK, it _is_ OK.

Can anyone say anything? 

Thanks,
Timur