when i migrated a SQLServer DB to a Oracle DB, Oaracle Migration report a lot of false info.

Tables :
Creating tongfang.null.null failed to map table :
oracle.mtg.migration.MigrationSQLException: cannot insert NULL into ("OM_OBJ_INFO"."OBJ_OWNER"):cannot insert NULL into ("OM_OBJ_INFO"."OBJ_OWNER")


Triggers
Creating tongfang.null. failed to map trigger :
oracle.mtg.migration.MigrationSQLException: cannot insert NULL into ("OM_OBJ_INFO"."OBJ_NAME"):cannot insert NULL into ("OM_OBJ_INFO"."OBJ_NAME")


Views
Creating tongfang.null. failed to map view :
oracle.mtg.migration.MigrationSQLException: cannot insert NULL into ("OM_OBJ_INFO"."OBJ_NAME"):cannot insert NULL into ("OM_OBJ_INFO"."OBJ_NAME")

how can i deal with these false info?

i have got a help info from the Oracle Technology Network:
Try one or both of the following:

You can resolve this by importing the correct Master database into the correct SQL Server, ie the SQL Server Server where your source database resides.

Use the sp_changedbowner stored procedure command in SQL Server to assign a valid login for the database user. This may be necessary if the SQL Server or Sybase database you are attempting to migrate was imported from another SQL Server database or Sybase database, which can cause the master databases to be out of sync


but i still dont know how to do. i am a tyro. who can tell me how to do?