Why isn't water coming out of a radiator in my freshly pressurized system?
I think you have a air lock.

Turn off all but one of the none working radiators, this will force the water to go do that radiator.  Then bleed the radiator and move onto the next one.  Do with with the pump running, but the boilder turned off (or turned down so it does not heat the water).

If that does not work, you will need to get someone in to flush the system. Don't overlook the option of just replacing all the pipework and radiators if you have a lot of sludge adn the system is old - then you will only have one trades person that is responible for all problems.