Warning: Wrong parameter count for mysql_connect()

I've a GNU/Linux Debian Woody, apache 1.3.26-0woody6, mysql 3.23.49-8.11, php4-mysql 4.1.2-7.0.1. Drupal 4.6.0

I've a problem with the installation, I think it's a bug. But I can be wrong.

The message It appears in the screen is this:

Warning: Wrong parameter count for mysql_connect() in /var/www/agic/includes/database.mysql.inc on line 32

In /var/www/agic/site/default/settings.php
I've
$db_url = 'mysql://webuser:mypass@localhost/web';

$base_url = 'http://www.mysite.org/agic

In deed, I can:

mysql -u webuser -p

and I can do:

mysql> use web;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed

and: 

mysql> show tables;
+--------------------------+
| Tables_in_web            |
+--------------------------+
| access                   |
| accesslog                |
| aggregator_category      |
| aggregator_category_feed |
| aggregator_category_item |
| aggregator_feed          |
| aggregator_item          |
| authmap                  |
| blocks                   |
| book                     |
| boxes                    |
| cache                    |
| comments                 |
| directory                |
| files                    |
| filter_formats           |
| filters                  |
| flood                    |
| forum                    |
| history                  |
| locales_meta             |
| locales_source           |
| locales_target           |
| menu                     |
| moderation_filters       |
| moderation_roles         |
| moderation_votes         |
| node                     |
| node_access              |
| node_comment_statistics  |
| node_counter             |
| permission               |
| poll                     |
| poll_choices             |
| profile_fields           |
| profile_values           |
| queue                    |
| role                     |
| search_index             |
| search_total             |
| sequences                |
| sessions                 |
| system                   |
| term_data                |
| term_hierarchy           |
| term_node                |
| term_relation            |
| term_synonym             |
| url_alias                |
| users                    |
| users_roles              |
| variable                 |
| vocabulary               |
| vocabulary_node_types    |
| watchdog                 |
+--------------------------+
55 rows in set (0.00 sec)

mysql>

I mean that the problem, I believe, It's the connection with the database in the source code.

Thanks :-)