epson rx425 printer ink cartridge replacement utility is greyed out?

I have loaded the driver but the ink cartridge replacement utility is greyed out and not working. How do I fix this so I know how much ink is left in the black and different colour cartridges. The ink light is flashing I don't know which one to change and I don't want to change them all and waste the ink - it is expensive to keep doing that. How do I acticate the ink cartridge replacement utility please