eval()’d code on line 4

hello, i have installed a plugin php_execution php to my wordpress website so that i can post in php. but i got this problem when i post in php code. Warning: mysql_connect(): Access denied for user xxxx @localhost (using password: YES) /home1/xxxx/public_html/xxxxxxxr.com/wp-content/plugins/php-execution-plugin/includes/class.php_execution.php(273) : eval()’d code on line 4

i got this code
/**
* execute php inside post
*/
270 function execute_php($content)
271 {
272 ob_start();
273 eval(“?>$content<?php “);
274 $html = ob_get_contents();
275 ob_end_clean();
276 return $html;
277 }

where is the problem and

how can i fix this problem?