the database owner has the following privilege:
SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, ALTER, INDEX

I was not able to reproduce your problem, the DB installs just fine for me.

Do you have any errors at Oracle level (e.g. in alert log) ? Are you sure the tables were not created in some other schema/database ?

I'm sure tables not be created, and alert log has no error.
Oracle version is 10.2.0.5
owner's privilege:
CREATE CLUSTER
CREATE INDEXTYPE
CREATE OPERATOR
CREATE PROCEDURE
CREATE SEQUENCE
CREATE SESSION
CREATE TABLE
CREATE TRIGGER
CREATE TYPE
UNLIMITED TABLESPACE

my install setting

Type of Database: Oracle
Hostname (for Database Server): my_db_server_ip:1521/sid
Username (for Database): mantis_owner
Password (for Database): mantis_owner_password
Database name (for Database): {empty}

the DB installs fine as the following settings:
Hostname (for Database Server): my_db_server_ip/sid <---- not set port
Username (for Database): mantis_owner
Password (for Database): mantis_owner_password
Database name (for Database): {empty}

does that mean oracle installation always use default port (1521)?

sorry about my mistake in installation settings.
Now I can install db and mantis work fine.

Please close or delete this issue, Thanks for your help.

does that mean oracle installation always use default port (1521)?

I would have to double-check exactly how the ADOdb library upon which we rely for database operations, handles Oracle connection settings, but IIRC you can give it a valid TNS string as hostname, like

(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=yourhost)(PORT=1523))(CONNECT_DATA=(SID=yoursid)))

I personally prefer to use a TNS name and define the connection details at system level (i.e. in tnsnames.ora or an OID ldap server)

There may be other ways. Refer to ADOdb documentation [1] for further details

[1] http://adodb.sourceforge.net/docs-adodb.htm