plesk 7.5 and the php parameter in url

[guguze]

hello,

two days ago i rent a virtual server at 1und1.de. running plesk 7.5 reloaded.
my partner set up his domain (so don´t know, what he did)
ok. the site is programmed in php with and the parts are loaded controlled by parameters in the url like :

www.domain.com?akt=hw

now, the url is correctly, but it always appears the default index content like there were no parameter given in the url.

so my question is how can i fix this?

thanks a lot

wolfram