I am trying to export the whole database under user system,
according to log file, the db was exported but unsuccessfully.
The last five lines are:

. exporting referential integrity constraints
. exporting synonyms
EXP-00008: ORACLE error 904 encountered
ORA-00904: invalid column name
EXP-00000: Export terminated unsuccessfully

My other database, which is also new install, works perfectly though.