[Boost-users] Linking problem trying to use mutex, condition

I'm trying to compile a test program using the ReadWriteMutex example at http://paulbridger.net/read_write_lock, and I'm getting about 30 linking errors referring to mutex, lock_error and the like. I'm on an Ubuntu system, using boost 1.33.1. I'm including "boost/thread/mutex.hpp" and "boost/thread/condition.hpp". I can post more details, but was wondering if anybody was familiar with this problem. thanks, brian