My radiators are not getting hot?

It sounds like you only have a single zone or one loop system. You may have to add another zone with it's own thermostat. This way if your problem bedroom still needs heat then the other zone will shut down and the problem zone will get the heat. It sounds like you did everything correct when you did it over. It just sounds like the radiators closest to the other side heat up the room before the problem room and shuts down. Shouldn't be a big expense and if you have a Handy Man (or Woman) into plumbing this can be done in a few hours or less. If the other radiators have shut off valves you could try shutting them down to half way and keep the bedroom on full. This way the heat won't get too warm real fast and shut down the thermostat.