DOCBOOK-APPS: Problems with dsssl and system identifiers

I write XML docbook, and when I try to use a system identifier, pointing to
the dtd, and parse it with dsssl and Openjade, I get the following error
messages: 

openjade:/home/knaving/docbook/dbpoolx.mod:735:34:E: omitted tag
minimization pa
rameter can be omitted only if "OMITTAG NO" is specified on the SGML
declaration
openjade:/home/knaving/docbook/dbpoolx.mod:756:40:E: omitted tag
minimization pa
rameter can be omitted only if "OMITTAG NO" is specified on the SGML
declaration

These are the first two - I got one for every line that looks like 
<!ELEMENT titleabbrev (%title.char.mix;)*> in dbpoolx.mod.

Has anyone ever had this problem before? 

                /Kristina Knaving