[Zope] Catalog addIndex Error

[beno]

Hi;
I tried to install a product called EMarket when I ran into this error 
)upon trying to set up EMarket from the eMarketAdd.dtml page):

Error Type: TypeError
Error Value: Catalog addIndex now requires the index type to be resolved 
prior to adding; create the proper index in the caller.

There is this line of code from addEMarket():
     newMainF.Catalog._catalog.addIndex('isAvailable','FieldIndex')

Clearly, by this point addEMarket() has been called, therefore, why is this 
not sufficient?
beno