Why won't Objectdock see my custom image?

I created a custom icon to use in Objectdock in Photoshop but cannot get Objectdock to display it in the Misc folder. My PNG file is in the Misc folder along with others that I downloaded -- and the others work fine. My PNG file seems to match all the specs of other PNG files that work.  I'd like to upload it here but there appears to be no provision for that. Any suggestions?