[Zope] TextIndexNG and mime type

I just installed TextIndexNG and I cannot seem to get it to create an index on existing catalog context. I keep getting the error(s): "text/x-unknown-content-type" not registered in registry "converters" or, "application/octet-stream" not registered in registry "converters" or something similar. The first error message occurs if the content_type is application/octet-stream. The second error occurs only on selected items that have content_type of application/pdf. Can anyone offer an idea as to what is going on? Thanks, Kevin