error_reporting(E_ALL) doesn't show anything

hi, in php.ini is error_reporting turned off. and, to see an error have to open error_log. though, for me is much easier to have it on and see the errors on the screen. while developing, of course. I put on the beginning of the file error_reporting(E_ALL) to "overwrite" php.ini but it doesn't work. still can't see anything. what am I doing wrong? thanks. -afan