LJ has changed the code for its userhead icons, and custom layout tiny icons don't show up properly.
fruitstyle has a Tiny Icon Generator which has been updated to reflect these changes and is a great help with re-coding:
http://fruitstyle.livejournal.com/44704.html It took me quite a bit of time to figure out the coding to change my icons on my own. The above generator is much more user friendly and time efficient. :) Very useful.