[Zope] More Missing ZClasses in Folder View

I am experiencing a weird problem. I have a zclass that extends ZObject and ZObject Manager. I have added it to a folder and it will not show up in the left hand folder tree view within the manage interface. I have had the zclass there for months and just noticed that it is not in the folder view. I have other zclasses that extend the same base objects and they work just fine. Any one know what the problem is? I also noticed a similar problems with ZClasses created with ZClassEvents. The are missing the ID in the folder view AND in the Catalog?? Seems strange. Thanks, Chris