will not clean the black out of the grouting out of tiles

I found it to make plenty of steam and the brush that is supplied with the cleaner when used with the jet nozzle
has no guts to when you try to clean the grouting; just using the jet nozzle on the grout will not remove the grime
ether the steamer dose not seem powerful enough.
As far as the floors go I do not know clean they are; the floor pad is fairly dirty and when i go over it again with a
clean pad that is dirty as well.