help with exec()...

I'm running with some trouble with exec(), system() and it's friends... I have a MySQL backup script that somewhere have something like $cmd="mysqldump ...... > somefile.sql"; if( !fopen("somefile.sql","r") ) { print error message }; $cmd is correct... I've copy-pasted it tons of times in the command shell and it worked... created the 'somefile.sql' and all. But none of the functions (exec, system..) works. When I use system it outputs me some header for mysqldump and that's all... I've also checked the directory with getcwd()... it is in the right dir to execute the mysqldump... I'm running PHP 4.06 in Apache 1.3.12 in a Win98 machine... what might be?