Did you wrote your own pages or using one generated from pagewizard?
i wrote my own ones and saw that metadata lines are working as described in the document Denon AVR Control protocol (RS-232). This seems like funky, but based on spec. i used metadata lines only showing information, if ipod is not playing. The driver includes variables (artist, title, album) für playing mode as well. You have to gamble with metadata info lines, to figure out the right displaying info. (My experience based on XP8, driver 1.1, D 4308 and ipod dock)