May I ask how you got this to work? I'm trying to use the "Multiple Attributes" dialog box to display census tracts as multi-colored graduated smbols. I specify the average age of admission and count of clients as the two value fields. I specify the age variable in the color ramp option and client count in the symbol size option. The closest I got was to color the census tracts with the average age range while showing the client count as a single-color graduated symbol. The symbol often covered the entire census tract, which is OK. I just wanted them to change colors. I finally used a separate layer for each age group so that I could color the graduated symbols as I needed to. Even then, I didn't see any solution for you to customize the legend. You might have to export the legend pieces one at a time as graphics and then pull them into the map.
... View more