[TYPO3] Warning: Access denied for user apache at localhost

[Miguel Angel Calleja Lázaro]

Hi, list, i have an error and i dont know whats matter:

I click on a link, this link takes me to a page. In this page i have a 
frontend plugin, well, error appears me on that line of plugin:

$con=mysql(TYPO3_db,$query); ---->line 128

And warning:
*Warning*: mysql(): Access denied for user: 'apache at localhost' (Using 
password: NO) in 
*/home/httpd/vhosts/host-sonoratec.biz/subdomains/sebastian/httpdocs/typo3conf/ext/login/pi1/class.tx_login_pi1.php* 
on line *128*

**What is happening to me? That had nerver passed  me, help please