how to add more .bro files in bro?

Thanks Michael Mirold for the answer of my last question.
When I want to use more .bro files, such as:
   ./bro -i eth0 ftp.bro http.bro,
then the program tell me that it can't go on when it analy the http.bro.
but when I use one .bro file , ftp.bro or http.bro ,they are all ok.