great..with your icon it's really nice!!! may i ask you a question? where did you find that icon for dropbox? it's quite a lot that i'm looking for something that fit with the elementary theme in such a good way! can you link it here?!?
Now log out and log back in and there should be the indicator icon. The default icon is an inbox, if you want to use mine here: [link] you have to unzip it into the icon theme folder inside of the folder /your-icon-theme-name/status/22