Sometimes there just isn't a code for every device in the remote, if the remote in question came with a TV or something, it's probably not one of the best universals on the market.
It might be time to get a good universal, I would recommend something like the One For All Cinema 7 or the Radio Shack 15-1994, both sell for between $25 and $30 and have a good selection of device codes. There's also the new RCA RCU810 that sells for about $50, which is worth checking out, it has Replay and TiVo codes too!
Rob.
http://www.hifi-remote.com