The entry for dblib.dsl points to lib/dblib.dsl, which doesn't exist (come
/usr/lib/sgml/lib is empty).
Do you have a small example document that triggers the problem?
I'm sorry, I can't easily supply an example, as our local system has been
patched to avoid this problem. I'm not sure I understand why you need an
example: the catalog file simply points to a non-existent file, so it won't be
found when it's required.
Our local fix for the problem was to link from /usr/lib/sgml/lib/dblib.dsl ->
But a proper fix should alter the path in the catalog.
Fixed in 1.57-2.