Thank you for thinking about my problem! More details are as follows.
DB2 Version 8.1.2. (It seems that I can insert binary strings using this DB2 version, since bind_param(... {TYPE => DBI::SQL_BINARY}) works well.)
OS: Linux, openSUSE 10.1.
There is no error message. However, character codes larger thatn 127 are reduced to a smaller value. For example, chr(0xe3) is changed to chr(0x1a). I find out the latter code by using a SELECT ASCII(col_name) FROM ... query.
Comment on Re^2: Updating/inserting Binary data using DBIx::Class