Need help with Rocket Dock icons

I installed RocketDock, and then installed Stack Docklets by placing the unzipped file in C/Program Files/Rocket Dock/Docklets. I downloaded some of new icons to add, but I can't figure out where to put them. I assign an icon to the Stack Docklet and it's fine until I shut down/restart and then all the icons revert back to the Default icon, including the default icons that came with...