sending headers

Hi List I am having trouble using headers. I try to include a redirect header in my script, but is fails with the familiar ( headers already sent) error. I KNOW you should put the headers call where it will cause the first output, and I do that, the only thing happening infront of the headers call is an include statement to my main db class; this class has absolutely NO output unless a function is called (which it is not)... What am I missing?