Oracle Message ORA-07472 - snclrd: open error when opening sgadef.dbf file.

ERRORsnclrd: open error when opening sgadef.dbf file.
CAUSEopen failed when opening the file ?/dbs/sgadef@.dbf
ACTIONCheck errno. Possible permission problem. Verify that the file ?/dbs/sgadef@.dbf exists.