Your server's RPT file is a log file created by Arma. It will be in the root directory of where your Arma is installed on the server and it's called arma2OAserver.rpt (I think?? lol can't remember now).
Is this server all yours? ie: you have complete control over it through RDP or some other remote access?
How are you starting the server? Are you just manually editing command line params? Are you using a launcher like Six-Updater? Is there more than one instance of Arma running on the server? Have you adjusted your .cfg files (server.cfg and basic.cfg)? How are you selecting the mission? Is it listed in your server.cfg file or are you just logging in and selecting the mission once you are in the server?
Also as Gunther mentioned have you installed Arma2 and Arma2 OA and have the server running as Combined Operations?
Sorry for all the questions but setting up a dedicated server properly with mods is not an easy task