(This is for 8.3.4 release candidate, but that is not
available in the 'Group' menu in the report form.)
library/encoding/tis-620.enc must have at least read
permissions for the world if it is to be installed
from a source tree mounted over NFS. Otherwise, root
cannot read the file.
In my case, the system was NFS mounted on a Linux box
in such a way that root is limited in scope.
A simple 'chmod +r library/encoding/tis-620.enc' does