mysql_* function error

[redundguy]

I work with PHP 4.2.2, with Apache.
When I use mysql_connect or another function in my php script I get the error:
"Error: Call to undefined function".
Why?
(The phpinfo() shows --with-mysql=shared,/usr' ')

[pyro]

Please post the code you were using to try to connect...

[redundguy]

I think that error is related to mysql.so extension.
So I enabled (uncomment) in my php.ini file:
extension=mysql.so
and also put mysql.so file in the directory specified in php.ini by extension_dir.
and restart http,
but my error remains:
mysql_connect() - Call to undefined function.