Here's the problem - there are several different kinds of California Black/Yellow plates.
[img]http://home.earthlink.net/~ajb44/ca_57_65.gif[/img]
YOM plates require 1962 or earlier plates, which are yellow background and black letter. Couple different formats for the earlier (10's and 20's) years. These have a STAMPED year of manufacture, or a METAL tag screwed on (red I think?) for some years.
You probably have a set of the later plates,with a STICKER representing the current registration year, not the YOM year. Can't be used for YOM.
Check out this page tons of license plate resources.
-Boyo
