I seem to have this problem my self. I can print from photoshop right to the oki printer and i get a royal blue but as soon as i open the photoshop file in the RIP i get a darker blue/purple as a preview and print. Other colours darken as well like green etc.
Is this a bug or the RIP just being daft and can’t get the right colour profile right? Its a few £££ to have some softwear that can’t print the right colours.