This means that greenstone could not resolve the name of
the index for searching at run time. There are normally
2 causes of this:

1) There is a problem with your system setup, and greenstone
can't read the 'gdbm' file containing the metadata. (or maybe
the collection didn't build properly)

2) You did not set the metadata in the collection's collect.cfg
file before building it. The normal way to do this is to
have a 'collectionmeta' item for each index. Eg:
(this is from the greenstone archives collect.cfg file)
indexes document:text document:From document:Subject
...
collectionmeta .document:text "Messages"
collectionmeta .document:From "From fields"
collectionmeta .document:Subject "Subject lines"

In future, you should tell us which version of greenstone you are using,
and what operating system you are using it on, if you want
people to be able to help you track down any problems.

John McPherson