Yes, the -206 indicates that the colimn in not known in the table. Thinks like this are always more easy in the db2-cli. Just connect and try the SQL. After that just type "db2 ? sql0206" and the error is explained.
What are you migrating? Just DB2 or a software package which uses DB2 and WAS? You have to go to the person or company who produces the SQL containing errors. This has nothing to do with migrating and everything with SQL and DDL.
I suggest you go to the CLI and execute "db2 describe table mbreel". This will punch the DDL of the table. My 'guess' is that either the column "ordermsgs_id" or "sequence" is missing because they are the only ones mentioned in the "where" clause.