problem with phprc var

hi. i have some trouble with an php5 installation used by an apache2 webserver and the suphp wrapper. when i want to use another php.ini for one of my vhosts and have set it via "setenv phprc /path/to/the/php/ini/dir" if i have an empty docroot with only one index.php including a "phpinfo();" then the phpinfo will not parse the custom php.ini. - the phprc var is set as wanted in the phpinfo output... but if I create an !empty! php.ini in the docroot the custom php.ini will get parsed and the phprc var is set also... i have to create the php.ini file for every subdir. and i am very confused ;-/ my versions: debian squeeze php 5.3.5-0.dotdeb.1 apache 2.2.16-6 suphp 0.7.1-1 thank you for your help