[Zope] progromattically keeping a zcatalog updated

I am not even sure if it is the zcatalog that is the problem. I add new instances of a class through dtml, then I go to a page which displays them, but sometimes the instances don't show up until I manually force the zcatalog to update. I have been using this: <dtml-call reindex_object> but I am not sure that it is right or maybe I am just using it incorectly josh oN